The vitalist and teleological idea of an internal principle of evolution, that determines the origin of animal and plant species independently of the environment and its conditions, is not only found in the "mechanical-physiological" theory of Nägeli, but also in several other attempts to explain the agencies of the transformation of species. All these efforts are welcomed by the academic philosophers with their Kantist dualism (mechanicism on the right, teleology on the left), and who are particularly anxious to save the supernatural element, Reinke's "cosmic intelligence," or the wisdom of the Creator, or the divine creative thought. All these dualistic and teleological efforts have the same fault: they overlook, or fail to appreciate properly, the immense influence of the environment on the shaping and modification of organisms. When, moreover, they deny progressive heredity and its connection with functional adaptation, they lose the chief factor in transformation. This applies also to the theory of germ-plasm.The desire to penetrate deeper into the mysterious processes that take place in the plasm in the physiological activities of heredity and adaptation has led to the formulation of a number of molecular theories. The chief of these are the pangenesis theory of Darwin (1878), my own perigenesis theory (1876), the idioplasm theory of Nägeli (1884), the germ-plasm theory of Weismann (1885), the mutation theory of De Bries, etc. As I havealready dealt with these in the sixth chapter (as well as in the ninth chapter of theHistory of Creation), I may refer the reader thereto. None of these or similar attempts has completely solved the very difficult problems in question, and none of them has been generally received. There is, however, one of them that we must consider more closely, because it is not only regarded by many biologists as the greatest advance of the theory of selection since Darwin, but it also touches the roots of several of the chief problems of biogeny. I mean the much-discussed germ-plasm theory of August Weismann (of Freiburg), one of our most distinguished zoologists. He has not only promoted the theory of descent by his many writings during the last thirty years, but has also put in its proper light the great importance and entire accuracy of the theory of selection. But, in his efforts to provide a molecular-physiological basis for it, he has proceeded by way of metaphysical speculation to frame a quite untenable theory of the plasm. While fully recognizing the ability and consistency and the able treatment which Weismann has shown, I am compelled once more to dissent from him. His ideas have recently been completely refuted by Max Kassowitz (1902) in hisGeneral Biology, and Ludwig Plate in the work I mentioned on the Darwinian principle of selection. We need not go into the details of the complicated hypothesis as to the molecular structure of the plasm which Weismann has framed in support of his theory of heredity—his theory of biophora, determinants, ideas, etc.—because they have no theoretical basis and are of no practical use. But we must pass some criticism on one of their chief consequences. In the interest of his complicated hypotheses, Weismann denies one of Lamarck's most important principles of transmutation—namely, the inheritance of acquired characters.When I made the first attempt in 1866 to formulatethe phenomena of heredity and adaptation in definite laws and arrange these in series, I drew a distinction between conservative and progressive heredity (chapter ix.,History of Creation). Conservative heredity, or the inheritance of inherited characters, transmits to posterity the morphological and physiological features which each individual has received from his parents. Progressive heredity, or the inheritance of acquired characters, transmits to offspring a part of those features which were acquired by the parents in the course of their individual lives. The chief of these are the characters that are caused by the activity of the organs themselves. Increase in the use of the organs causes a greater access of nourishment and promotes their growth; decrease in the exercise of organs has the contrary effect. We have examples at hand in the modification of the muscles or the eyes, the action of the hand or throat in painting or singing, and so on. In these and all the arts the rule is: Practice makes perfect. But this applies almost universally to the physiological activity of the plasm, even its highest and most astounding function—thought; the memory and reasoning capacity of the phronema are improved by constant exercise of the cells which compose this organ, just as we find in the case of the hands and the senses.Lamarck recognized the great morphological significance of this physiological use of the organs, and did not doubt that the modification caused was transmitted to offspring to a certain extent. When I dealt with this correlation of direct adaptation and progressive heredity in 1866, I laid special stress on the "law of cumulative adaptation" (General Morphology, ii., p. 208). "All organisms undergo important and permanent (chemical, morphological, and physiological) changes when acted on by a change in its life-conditions, slight in itself, but continuing for a long time or being frequently repeated."At the same time I pointed out that in this case two groups of phenomena are closely connected which are often separated—namely, cumulative heredity: firstlyexternal, by the action of the external conditions (food, climate, environment, etc.), and secondlyinternal, by the reaction of the organism, the influence of internal conditions (habit, use and disuse of organs, etc.). The action of outer influences (light, heat, electricity, pressure, etc.) not only causes a reaction of the organism affected (energy of movement, sensation, chemosis, etc.), but it has an especial effect as a trophic stimulus on its nutrition and growth. The latter element has been particularly studied by Wilhelm Roux; his functional adaptation (1881) coincides with my cumulative adaptation, the close relation of which to correlative adaptation I had pointed out in 1866. Plate has recently given this "definitely directed variation" the name of ectogenetic orthogenesis, or, briefly, ectogenesis.The controversy about progressive heredity still continues here and there. Weismann completely denies it, because he cannot bring it into harmony with his germ-plasm theory, and because he thinks there are no experimental proofs in support of it. A number of able biologists agree with him, led away by his brilliant argumentation. However, many of them foolishly lay great stress on experiments in heredity which prove nothing; for instance, the fact that the offspring of a mammal that has had its tail cut off do not inherit the feature. A number of recent observations seem to prove that in a few cases even defects of this sort (when they have caused profound and lasting disease of the part affected) may be transmitted to offspring. However, as far as the formation of new species is concerned, the fact is of no consequence; in this it is a question of cumulative or functional adaptation. Experimental proofs of this are difficult to find, if one wants a strict demonstrationof the type of physical experiments; the biological conditions are generally too complicated and offer too many weak points to rigorous criticism. The beautiful experiments of Standfuss and C. Fisher (Zurich) have shown that changes in the environment (such as temperature or food) can cause striking modifications that are transmitted to offspring. In any case, there are plenty of luminous proofs of progressive heredity in the vast arsenal of morphology, comparative anatomy, and ontogeny.Comparative anatomy affords a number of most valuable arguments for other phylogenetic questions as well as progressive heredity; and the same may be said of comparative anatomy and comparative ontogeny. I have collected and illustrated a good many of these proofs in the new edition of myAnthropogeny. However, in order to understand and appreciate them aright, the reader must have some acquaintance with the methods of critical comparison. This means not only an extensive knowledge of anatomy, ontogeny, and classification, but also practice in morphological thinking and reasoning. Many of our modern biologists lack these qualifications, especially those "exact" observers who erroneously imagine they can understand vast groups of phenomena by accurate description of detailed microscopic structures, etc. Many distinguished cytologists, histologists, and embryologists have completely lost the larger view of their work by absorption in these details. They even reject some of the fundamental ideas of comparative anatomy, such as the distinction between homology and analogy; Wilhelm His, for instance, declared that these "academic ideas" are "unreliable tools." On the other hand, physiological experiments ought to contribute to the solution of morphological problems, and of these they can say nothing. To show the incalculable value of comparative anatomy for phylogeny,I need only point to one of its most successful departments, the skeleton of the vertebrates, the comparison of the various forms of the skull, the vertebral column, the limbs, etc. It is not in vain that for more than a hundred years gifted scientists, from Goethe and Cuvier to Huxley and Gegenbaur, have devoted years of laborious research to the methodical comparison of these similar yet dissimilar forms. They have been rewarded by the discovery of the common laws of structure, which can only be explained in the sense of modern evolution by descent from common ancestors.We have a striking example of this in the limbs of mammals, which, with the same internal skeletal structure, show a very great variety in outer form—the slender bones of the running carnivora and ungulates, the oar-bones of the whale and seal, the shovel-bones of the mole and hypudæus, the wings of the bat, the climbing bones of the ape, and the differentiated limbs of the human body. All these different skeletal forms have descended from the same common stem-form of the oldest Triassic mammals; their various forms and structures are adapted in scores of ways to different functions; but they risethroughthese functions, and all these functional adaptations can only be understood by progressive heredity. The theory of germ-plasm gives no causal explanation whatever of them.The majority of recent biologists are of opinion that of the two chief constituents of the nucleated cell the cytoplasm of the cell-body discharges the function of nutrition and adaptation, while the caryoplasm of the nucleus accomplishes reproduction and heredity. I first advanced this view in the ninth chapter of theGeneral Morphology(in 1866); and it was afterwards solidly and empirically established by the excellent investigations of Eduard Strasburger, the brothers Oscar and Richard Hertwig, and others. The elaborate finer structures which theseobservers discovered in cell-division led to the theory that the colorable part of the nucleus, chromatin, is the real hereditary matter, or the material substratum of the energy of heredity. Weismann added the theory that this germ-plasm lives quite separately from the other substances in the cell, and that the latter (the soma-plasm) cannot transmit to the germ-plasm the characters it has acquired by adaptation. It is on the strength of this theory that he opposes progressive heredity. The representatives of the latter (including myself) do not accept this absolute separation of germ-plasm from body-plasm; we believe that even in the process of cell-division in the unicellular organism there is partial blending of the two kinds of plasm (caryolysis), and that in the multicellular organism of the histona also the harmonious connection of all the cells by their plasma-fibres makes it possible enough for all the cells in the body to act on the germ-plasm of the germ-cells. Max Kassowitz has shown how we can explain this influence by the molecular structure of the plasm.At the beginning of the twentieth century a new biological theory aroused a good deal of interest, and was welcomed by some as an experimental refutation of Darwin's theory of selection and by others as a valuable supplement to it. The distinguished botanist Hugo de Bries (of Amsterdam) gave an interesting lecture at the scientific congress at Hamburg in 1901 on "The Mutations and Mutation-periods in the Origin of Species." Supported by many years of experiments in selection and some ingenious speculations, he thinks he has discovered a new method of the transformation of species, an abrupt modification of the specific form at a bound, and so discredited Darwin's theory of their gradual change through long periods of time. In a large work onExperiments and Observations on the Origin of Species in the Plant Kingdom(1903), De Bries has endeavored todemonstrate the truth of his theory of mutation. The warm approval which it won from a number of eminent botanists, and especially vegetal physiologists, was not shared by zoologists. Of these Weismann, in hisLectures on the Theory of Descent(1902, ii. p. 358), and Plate in hisProblems of Species-formation(1903, p. 174), have dealt fully with the theory of mutation, and, while appreciating the interesting observations and experiments of De Bries, have rejected the theory he has built on them. As I share their opinion, I may refer the reader who is interested in these difficult problems to their works, and will restrict myself here to the following observations. The chief weakness of the theory of mutation of De Bries is on its logical side, in his dogmatic distinction between species and variety, mutation and variation. When he holds the constancy of species as a fundamental "fact of observation," we can only say that this (relative) permanence of species is very different in the different classes. In many classes (for instance, insects, birds, many orchids and graminea) we may examine thousands of specimens of a species without finding any individual differences; in other classes (such as sponges, corals, in the generarubusandhieracium) the variability is so great that classifiers hesitate to draw up fixed species. The marked difference between various forms of variability which De Bries alleges cannot be carried through; the fluctuating variations (which he takes to be unimportant) cannot be sharply distinguished from the abrupt mutations (from which new species are supposed to result at a bound). De Bries's mutations (which I distinguished in theGeneral Morphologyas "monstrous changes" from other kinds of variation) must not be confused with the paleontological mutations of Waagen (1869) and Scott (1894) which have the same name. The sudden and striking changes of habit which De Bries observed onlyin one single species ofœnotheravery rarely occur, and cannot be regarded as common beginnings of the formation of new species. It is a curious freak of chance that this species bears the nameœnothera Lamarckiana; the views of the great Lamarck on the powerful influence of functional adaptation have not been refuted by De Bries. It must be carefully noted, in fact, that De Bries is firmly convinced of the truth of Lamarck's theory of descent, like all competent modern biologists. This must be well understood, because recent metaphysicians see in the supposed refutation of Darwinism the death of the whole theory of transformism and evolution. When they appeal in this sense to its most virulent opponents, Dennert, Driesch, and Fleischmann, we may remind them that the curious sermons of these minor sophists are no longer noticed by any competent and informed scientist.Not only in the brilliant speculations of De Bries and Nägeli, but also in many other botanical works that have lately attempted to advance the theory of descent, we find a striking difference from the prevailing views of zoologists in the treatment of a number of general biological problems. This difference is, of course, not due to a disproportion of ability in the two great and neighboring camps of biology, but to the differences in the phenomena that we observe in plant life on the one hand and animal life on the other. It must be noted particularly that the organism of the higher animals (including our own) is much more elaborately differentiated in its various organs and much more exposed to our direct experience than that of the higher plants. The chief properties and activities of our muscles, skeleton, nerves, and sense-organs, are understood at once in comparative anatomy and physiology. The study of the corresponding phenomena in the bodies of the higher plants is much more difficult. The features ofthe innumerable elementary organs in the cell-monarchy of the animal body are much more intricate, yet at the same time much more intelligible, than those of the cell-republic of the higher plant-body. Thus the phylogeny of the plants encounters much greater difficulties than that of the animals; the embryology of the former says much less in detail than that of the latter. We can understand, therefore, why the biogenetic law is not so generally recognized by botanists as by zoologists. Paleontology, which provides such valuable fossil material for many groups of the animal kingdom that we can more or less correctly draw up their ancestral tree on the strength of this, gives us very little for most groups of the plant kingdom. On the other hand, the large and sharply demarcated plant-cell, with its various organella, is much more valuable in connection with many problems than the tiny animal-cell. For many physiological purposes, in fact, the higher plant body is more accessible to exact physical and chemical research than the higher animal body. The antithesis is less in the kingdom of the protists, as the difference between animal and vegetal life is mostly confined to difference of metabolism, and finally disappears altogether in the province of the unicellular forms of life. Hence, for a clear and impartial treatment of the great problems of biology, and especially of phylogeny, it is imperative to have a knowledge of both zoological and botanical investigation. The two great founders of the theory of descent—Lamarck and Darwin—were able to penetrate so deeply into the mysteries of organic life and its development because they had extensive attainments both in botany and zoology.Of the various tendencies that have recently made their appearance among zoologists and botanists in the discussion of the theory of descent, we frequently find Neo-Lamarckism and Neo-Darwinism distinguished asopposing schools. This opposition has no meaning unless we understand by it the alternatives of transformism—with or without the theory of selection. The one principle that distinguishes Darwinism proper from the older Lamarckism is the struggle for existence and the theory of selection based on it. It is quite wrong to make the test an acceptance or rejection of progressive heredity. Darwin was just as firmly convinced as Lamarck or myself of the great importance of the inheritance of acquired characters, and particularly of the inheritance of functional adaptations; he merely ascribed to it a more restricted sphere of influence than Lamarck. Weismann, however, denies progressive heredity altogether, and wants to trace everything to "the omnipotence of natural selection." If this view of Weismann and the theory of germ-plasm he has based on it are correct, he alone has the honor of founding a totally new (and in his opinion very fruitful) form of transformism. But it is quite wrong to describe this Weismannism as Neo-Darwinism, as frequently happens in England. It is just as wrong to call Nägeli, De Bries, and other modern biologists who reject selection Neo-Lamarckists.If the theory of descent is right, as all competent biologists now admit, it puts on morphology the task of assigning approximately the origin of each living form. It must endeavor to explain the actual organization of each by its past, and to recognize the causes of its modification in the series of its ancestors. I made the first attempt to achieve this difficult task in founding stem-history or phylogeny as an independent historical science in my "General Evolution" (in the second volume of theGeneral Morphology). With it I associated as a second and equally sound part ontogeny; I understood by this the whole science of the development of the individual, both embryology and metamorphology. Ontogeny enjoys the privileges (especially in the wayof certainty) of a purely descriptive science, when it confines itself to the faithful description of the directly observed facts, either the embryonic processes in the womb or the later metamorphic processes. The task of phylogeny is much more difficult, as it has to decipher long-past processes by means of imperfect evidence, and has to use its documents with the utmost prudence.The three most valuable sources of evidence in phylogeny are paleontology, comparative anatomy, and ontogeny. Paleontology seems to be the most reliable source, as it gives us tangible facts in the fossils which bear witness to the succession of species in the long history of organic life. Unfortunately, our knowledge of the fossils is very scanty and often very imperfect. Hence the numerous gaps in its positive evidence have to be filled up by the results of two other sciences, comparative anatomy and ontogeny. I have dealt fully with this in myAnthropogeny. As I have also spoken of the general features of these phyletic evidences in the sixteenth chapter of theHistory of Creation, I need do no more here than repeat that it is necessary to make equal and discriminating use of all three classes of documents if we are to attain the aim of phylogeny correctly. Unfortunately, this necessitates a thorough knowledge of all three sciences, and this is very rare. Most embryologists neglect paleontology, most paleontologists embryology, while comparative anatomy, the most difficult part of morphology, involving most extensive knowledge and sound judgment, is neglected by both. Besides these three sources of phylogeny there is valuable proof afforded by every branch of biology, especially by chorology, œcology, physiology, and biochemistry.Although there has been very extensive phylogenetic research during the last thirty years, and it has yielded a number of interesting results, many scientists still seemto look on them with a certain distrust; some contest their scientific value altogether, and say that they are nothing but airy and untenable speculations. This is especially the case with many physiologists who look upon experiment as the only exact method of investigation, and many embryologists who think their sole task is description. In view of these sceptical strictures, we may recall the history and the nature of geology. No one now questions the great importance and the various uses of this science, although in it there is no possibility of directly observing the historical processes as a rule. No scientist now doubts that the three vast successive formations of the Mesozoic Period—the Triassic, Jurassic, and Cretaceous—have been formed from sea-deposits (lime, sandstone, and clay), though no one was a witness to the actual formation; no one doubts to-day that the fossil skeletons of fishes and reptiles which we find in these groups are not mysterious freaks of nature, but the remains of extinct fishes and reptiles that lived on the earth during those millions of years long ago. And when comparative anatomy shows us the genealogical connection of these related forms, and phylogeny (with the aid of ontogeny) constructs their ancestral trees, their historical hypotheses are just as sound and reliable as those of geology; the only difference is that the latter are much simpler, and thus easier to construct. Phylogeny and geology are, in the nature of the case,historical sciences.Hypotheses are necessary in phylogeny and geology, where the empirical evidence is incomplete, as in every other historical science. It is no detraction from the value of these to urge that they are sometimes weak and have to be replaced by better and stronger ones. A weak hypothesis is always better than none. We must, therefore, protest against the foolish dread of hypotheses which is urged against our phylogenetic methods by therepresentatives of the exact and descriptive sciences. This shrinking from hypotheses often hides a defective knowledge of other sciences, an incapacity for synthetic thought, and a feeble sense of causality. The delusions into which it leads many scientists may be seen from the fact that chemistry, for instance, is reckoned an "exact" science; yet no chemist has ever seen the atoms and molecules of compounds with which he is occupied daily, or the complicated relations on the assumption of which the whole of modern structural chemistry is based. All these hypotheses rest on inferences, not on direct observation.I have, from the first, insisted on the close causal connection between ontogeny and phylogeny, ever since I distinguished these two parts of biogeny in the fifth book of theGeneral Morphology. I also laid stress on the mechanical character of these sciences, and endeavored to give a physiological explanation of their morphological phenomena. Until then embryology had been regarded as a purely descriptive science. Carl Ernst Baer, who had provided a solid foundation for it in his classicAnimal Embryology(1828), was convinced that all the phenomena of individual development might be reduced to the laws of growth; but he was quite unconscious of the real direction of this growth, its "purposiveness," the real causes of construction. The distinguished Würtzburg anatomist, Albert Kölliker, whoseManual of Human Embryology(1859) gave the first comprehensive treatment of the science from the cellular point of view, adhered, even in the fourth edition (1884), to the opinion that "the laws of the development of the organism are still completely unknown." In opposition to this generally received opinion, I endeavored, in 1866, to prove that Darwin had, by his improvement of the theory of descent, not only solved the phylogenetic problem of the origin of species,but, at the same time, given us the key to open the closed doors of embryology, and to learn the causes of the ontogenetic processes as well. I formulated this view in the twentieth chapter of theGeneral Morphology, in forty-four theses, of which I will quote only the following three: 1. The development of organisms is a physiological process, depending on mechanical causes, or physico-chemical movements. 40. Ontogenesis, or the development of the organic individual, is directly determined by phylogenesis, or the evolution of the organic stem (phylon) to which it belongs. 41. Ontogenesis is a brief and rapid recapitulation of phylogenesis, determined by the physiological functions of heredity and adaptation. The pith of my biogenetic principle is expressed in these and the remaining theses on the causal nexus of biontic and phyletic development. At the same time I make it quite clear that I reduce the physical process of ontogenesis, and also phylogenesis, to a pure mechanics of the plasm (in the sense of the critical philosophy).The comprehensive fundamental law of organic development was briefly formulated by me in the fifth book of theGeneral Morphologyand in the tenth chapter of theHistory of Creation(developed more fully in the fourteenth chapter of the tenth edition, 1902). I afterwards sought to establish it securely in two different ways. In the first place, I proved in myStudies of the Gastræa Theory(1872-1877) that in all the tissue-animals, from the lowest sponges and polyps to the highest articulata and vertebrates, the multicellular organism develops from the same primitive embryonic form (thegastrula), and that this is the ontogenetic repetition, in virtue of heredity, of a corresponding stem-form (thegastræa). In the second place, I made the first attempt in myAnthropogeny(1874) to illustrate this recapitulation theory from the instance of our own human organism,by trying to explain the complex process of individual development, for the whole frame and every single part of it, by causal connection with the stem-history of our animal ancestors. In the latest edition of this monistic "ontogeny of man" I gave numbers of illustrations (thirty plates and five hundred engravings) of these intricate structures, and endeavored to make the subject still plainer by the addition of sixty genetic tables. I may refer the reader to this work,[10]and not dwell any further here on the biogenetic law, especially as one of my pupils, Heinrich Schmidt (of Jena), has recently described its biological significance and its earlier history and present position in a very clear and reliable little work (Haeckel's Biogenetic Law and its Critics). I will only add a word or two on the struggle that has taken place for thirty years over the complete or partial recognition of the biogenetic law, its empirical establishment, and its philosophic application.In the very name, "fundamental law of biogeny," which I have given to my recapitulation theory, I claim that it is universal. Every organism, from the unicellular protists to the cryptogams and cœlenteria, and from these up to the flowering plants and vertebrates, reproduces in its individual development, in virtue of certain hereditary processes, a part of its ancestral history. The very word "recapitulation" implies a partial and abbreviated repetition of the course of the original phyletic development, determined by the "laws of heredity and adaptation." Heredity brings about the reproduction of certain evolutionary features; adaptation causes a modification of them by the conditions of the environment—a condensation, disturbance, or falsification. Hence I insisted from the first that the biogenetic law consists of two parts, one positive and palingeneticand the other restrictively negative and cenogenetic.Palingenesisreproduces a part of the original history of the stem;cenogenesisdisturbs or alters this picture in consequence of subsequent modifications of the original course of development. This distinction is most important, and cannot be too often repeated in view of the persistent misunderstanding of my opponents. It is overlooked by those who (like Plate and Steinmann) grant it only a partial validity, and by those who reject it altogether (like Keibel and Hensen). The embryologist Keibel is the most curious of these, as he has himself afforded a good many proofs of the biogenetic law in his careful descriptive-embryological works. But he has so little mastered it that he has never understood the distinction between palingenesis and cenogenesis.It is especially unfortunate that one of our most distinguished embryologists, Oscar Hertwig, of Berlin, who provided a good deal of evidence in favor of the biogenetic law thirty years ago, has lately joined the opponents of it. His supposed "correction" or modification of it is, as Keibel has rightly said, a complete abandonment of it. Heinrich Schmidt has partly explained the causes of this change in his work on the biogenetic law. They are not unconnected with the psychological metamorphosis which Oscar Hertwig has undergone at Berlin. In the discourse on "The Development of Biology in the Nineteenth Century," which he delivered at the scientific congress at Aachen in 1900, he openly accepted the dualist principles of vitalism (although he says they are "just as unreliable as the chemico-physical conception of the opposing mechanical school"). The views which he has lately advanced on the worthlessness of Darwinism and the unreliability of phylogenetic hypotheses are diametrically opposed to the opinions he represented at Jena twenty-five years ago, and to those which hisbrother, Richard Hertwig, of Munich, has consistently maintained in his admirableManual of Zoology.In opposition to the mechanical ontogeny which I formulated in 1866 and embodied in the biogenetic law, a number of other tendencies in embryology afterwards appeared, and, with the common title of "mechanical embryology," branched out in every direction. The chief of these to attract attention thirty years ago were the pseudo-mechanical theories of Wilhelm His, who has rendered great service to ontogeny by his accurate descriptions and faithful illustrations of vertebrate-embryos, but who has no idea of comparative morphology, and so has framed the most extraordinary theories about the nature of organic development. In hisStudy of the First Sketch of the Vertebrate-body(1868), and many later works, His endeavored to explain the complicated ontogenetic phenomena on direct and simple physical lines by reducing them to elasticity, bending, folding of the embryonic layers, etc., while explicitly rejecting the phylogenetic method; he says that this is "a mere by-way, and quite unnecessary for the explanation of the ontogenetic facts (as direct consequences of physiological principles of development)." As a matter of fact, nature rather plays the part of an ingenious tailor in His's pseudo-mechanical and tectogenetic speculations, as I have shown in the third chapter of theAnthropogeny. Hence they have been humorously called the "tailor theory." However, they misled a few embryologists by opening the way to a direct and purely mechanical explanation of the complex embryonic phenomena. Although they were at first much admired, and immediately afterwards abandoned, they have found a number of supporters lately in various branches of embryology.The great success that modern experimental physiology achieved by its extensive employment of physicaland chemical experiments inspired a hope of attaining similar results in embryology by means of the same "exact" methods. But the application of them in this science is only possible to a slight extent on account of the great complexity of the historical processes and the impossibility of "exactly" determining historical matters. This is true of both branches of evolution, individual and phyletic. Experiments on the origin of species have very little value, as I said before; and this is generally true of embryological experiments also. However, the latter, especially careful experiments on the first stages of ontogenesis, have yielded some interesting results, particularly in regard to the physiology and pathology of the embryo at the earliest stages of development. TheArchiv für Entwickelungsmechanik, which is edited by the chief representative of this school, Wilhelm Roux, contains, besides these valuable inquiries, a good number of ontogenetic articles, which partly rely on and partly ignore the biogenetic law.Psychology and biogeny have been up to the present regarded as the most difficult branches of biology for monistic explanation, and the strongest supports of dualistic vitalism. Both departments become accessible to monism and a mechanico-causal explanation by means of the biogenetic law. The close correlation which it establishes between individual and phyletic development, and which depends on the interaction of heredity and adaptation, makes it possible to explain both. In regard to the first, I formulated the following principle thirty years ago in my first study of the gastræa theory: "Phylogenesis is the mechanical cause of ontogenesis." This single principle clearly expresses the essence of our monistic conception of organic development:In the future every student will have to declare himself for or against this principle, if in biogeny he is not content with a mere admiration of the wonderful phenomena, but desires to understandtheir significance. The principle also makes clear the wide gulf that separates the older teleological and dualistic morphology from the modern mechanical and monistic science. If the physiological functions of heredity and adaptation are proved to be the sole causes of organic construction, every kind of teleology, and of dualistic and metaphysical explanation, is excluded from the province of biogeny. The irreconcilable opposition between the leading principles of the two is clear. Either there is or is not a direct and causal connection between ontogeny and phylogeny. Either ontogenesis is a brief compendium of phylogenesis or it is not. Either epigenesis and descent—or pre-formation and creation.In repeating these principles here, I would lay stress particularly on the fact that, in my opinion, our "mechanical biogeny" is one of the strongest supports of the monistic philosophy.XVIITHE VALUE OF LIFEChanges of life—Aim of life—Progress of life—Historic aims—Historic waves—Value of life in classes and races of men—Psychology of uncivilized races—Savages—Barbarians—Civilized nations—Educated nations—Three stages of development (lower, middle, and higher) in each of the four classes—Individual and social value of civilized life in the five sections of nutrition, reproduction, movement, sensation, and mental life—Estimate of human life.The value of human life is seen by us to-day, now that evolution is established, in quite a different light from fifty years ago. We are now accustomed to regard man as a natural being, the most highly developed natural being that we know. The same "eternal iron laws" that rule the evolution of the whole cosmos control our own life. Monism teaches that the universe really deserves its name, and is an all-embracing unified whole—whether we call it God or Nature. Monistic anthropology has now established the fact that man is but a tiny part of this vast whole, a placental mammal, developed from a branch of the order of primates in the later Tertiary Period. Hence, before we seek to estimate the value of man's life, we will cast a glance at the significance of organic life generally.An impartial survey of the history of organic life on our planet teaches, first of all, that it is a process of constant change. Millions of animals and plants die every second, while other millions replace them; every individualhas his definite period of life, whether it lives only a few hours, like the one-day fly or the infusorium, or, like the Wellingtonia, the dragon-tree of Orotava, and many other giant trees, lives for thousands of years. Even the species, the collection of like individuals, is just as transitory, and so are the orders and classes that embrace numbers of species of animals and plants. Most species are confined to a single period of the organic history of the earth; few species or genera pass unchanged through several periods, and not a single one has lived in all the periods. Phylogeny, taking its stand on the facts of paleontology, teaches unequivocally that every specific living form has only existed a longer or shorter period in the course of the many (more than a hundred) million years which make up the history of organic life.Every living being is an end to itself. On this point all unprejudiced thinkers are agreed, whether, like the teleologist, they believe in an entelechy or dominant as regulator of the vital mechanism, or whether they explain the origin of each special living form mechanically by selection and epigenesis. The older anthropistic idea, that animals and plants were created for man's use, and that the relations of organisms to each other were generally regulated by creative design, is no longer accepted in scientific circles. But it is just as true of the species as of the individual that it lives for itself, and looks above all to self-maintenance. Its existence and "end" are transitory. The progressive development of classes and stems leads slowly but surely to the formation of new species. Every special form of life—the individual as well as the species—is therefore merely a biological episode, a passing phenomenal form in the constant change of life. Man is no exception. "Nothing is constant but change," said the old maxim.The historical succession of species and classes is, bothin the animal and the plant kingdom, accompanied by a slow and steady progress in organization. This is directly and positively taught by paleontology; its creation-medals, the fossils, are unequivocal and irrefutable witnesses to this phylogenetic advance. I have dealt with the subject in myHistory of Creation, and at the same time shown that both the progressive improvement and the increasing variety of the species can be explained mechanically as necessary consequences of selection. There was no need of a conscious Creator or a transcendental purposiveness to effect this. Scientific and thorough proof of this will be found in the three volumes of mySystematic Phylogeny(1894). I need only refer briefly to the two conspicuous examples we have in the stem-history of the tissue-plants and that of the vertebrates. Of the metaphyta the ferns are the chief groups in the Paleozoic, the gymnosperms in the Mesozoic, and the angiosperms in the Cenozoic age. Of the vertebrates only fishes are found in the Silurian age, dipneusta only begin in the Devonian, and the first mammals are in the Triassic.A number of false teleological conclusions have been drawn from these facts of progressive modification of forms, as they are given in paleontology. The latest and most developed form of each stem was taken to be the preconceived aim of the series, and its imperfect predecessors were conceived as preparatory stages to the attainment of this aim. It was like the conduct of many historians, who, when a particular race or state has reached a high rank in civilization as a result of its natural endowments and favorable conditions of development, hail it as a "chosen people," and regard its imperfect earlier condition as a deliberately conceived preparatory stage. In point of fact, these evolutionary stages were bound to proceed according as the internal structure (given by heredity) and the outer conditions(provoking adaptation) determined. We cannot admit any conscious direction to a certain end, either in the form of theistic predestination or pantheistic finality. For this we must substitute a simple mechanical causality in the sense of psycho-mechanical monism or hylozoism.Although the stem-history of plants and animals, like the history of humanity, shows a progressive advance taken as a whole, we find a good deal of vacillation in detail. These historical waves are wholly irregular; in periods of decay the hollows of the waves often persist for a long time, and are then succeeded by a fresh rise to the crest of another wave. New and rapidly advancing groups come to take the place of the old decaying groups, bringing with them a higher stage of organization. Thus, for instance, the ferns of to-day are only a feeble survival of the huge and varied pteridophyta that formed the most conspicuous part of the paleozoic forests in the Devonian and Carboniferous periods; they were ousted in the Secondary Period by their gymnosperm descendants (cycadea and conifers), and these, again, in the Tertiary Period by the angiosperm flowering plants. So among the terrestrial reptiles the modern tortoises, serpents, crocodiles, and lizards are only a feeble remnant of the enormous reptile-fauna that dominated the Secondary Period, the colossal dinosauri, pterosauri, ichtyosauri, and plesiosauri. They were replaced in the Tertiary Period by the smaller but more powerful mammals. In the history of civilization the Middle Ages form a deep valley between the crests of the waves of classical antiquity and modern culture.These few examples suffice to show that the various classes and orders of living things have a very different value when compared with each other. In regard to their intrinsic aim, self-maintenance, it is true that all organisms are on a level, but in their relations to other living things and to nature as a whole they are of veryunequal value. Not only may larger animals and plants retain domination for a long time in virtue of their special use or superior force and mass, but small ones may prevail owing to their power of inflicting injury (bacteria, fungi, parasites, etc.). In the same way the value of the various races and nations is very unequal in human history. A small country like Greece has almost dominated the mental life of Europe for more than two thousand years in virtue of its superior culture. On the other hand, the various tribes of American Indians have, it is true, developed a partial civilization in some parts (Peru and Central America); but, on the whole, they have proved incapable of advancing.Though the great differences in the mental life and the civilization of the higher and lower races are generally known, they are, as a rule, undervalued, and so the value of life at the different levels is falsely estimated. It is civilization and the fuller development of the mind that makes civilization possible, that raise man so much above the other animals, even his nearest animal relatives, the mammals. But this is, as a rule, peculiar to the higher races, and is found only in a very imperfect form or not at all among the lower. These lower races (such as the Veddahs or Australian negroes) are psychologically nearer to the mammals (apes or dogs) than to civilized Europeans; we must, therefore, assign a totally different value to their lives. The views on the subject of European nations which have large colonies in the tropics, and have been in touch with the natives for centuries, are very realistic, and quite different from the ideas that prevail in Germany. Our idealistic notions, strictly regulated by our academic wisdom and forced by our metaphysicians into the system of their abstract ideal-man, do not at all tally with the facts. Hence we can explain many of the errors of the idealistic philosophy and many of the practical mistakes that havebeen made in the recently acquired German colonies; these would have been avoided if we had had a better knowledge of the low psychic life of the natives (cf.the writings of Gobineau and Lubbock).The grave errors that have been maintained in psychology for centuries are mostly due to a neglect of the comparative and genetic methods and the narrow employment of self-observation, or the introspective method; they are also partly due to the fact that metaphysicians generally make their own highly developed mind—a scientifically trained reason—the starting-point of their inquiry, and regard this as representative of the human mind in general, and thus build up their ideal scheme. The gulf between this thoughtful mind of civilized man and the thoughtless animal soul of the savage is enormous—greater than the gulf that separates the latter from the soul of the dog. Kant would have avoided many of the defects of his critical philosophy, and would not have formulated some of his powerful dogmas (such as the immortality of the soul, or the categorical imperative) if he had made a thorough and comparative study of the lower soul of the savage, and phylogenetically deduced the soul of civilized man therefrom.The extreme importance of this comparison has only been fully appreciated of late years (by Lubbock, Romanes, etc.). Fritz Schultze (of Dresden) made the first valuable attempt in his interestingPsychology of the Savage(1900) to give us an "evolutionary psychological description of the savage in respect of intelligence, æsthetics, ethics, and religion." At the same time, he gives us "a history of the natural creation of the human imagination, will, and faith." The first book of this important work deals with thought, the second with will, and the third with the religious ideas of the savage, or "the story of the natural evolution of religion" (fetichism,animism, worship of the heavenly bodies). In an appendix to the second book the author deals with the difficult problems of evolutionary ethics, supporting himself by the authority of the great work of Alexander Sutherland,The Origin and Growth of the Moral Instinct(1898). Sutherland divides humanity, in regard to the various stages of civilization and mental development (not according to racial affinity), into four great classes: 1, Savages; 2, barbarians; 3, civilized races; 4, educated races. As this classification of Sutherland's not only enables us to take a good survey of the various forms of mental development, but is also very useful in connection with the question of the value of life at the different stages, I will briefly reproduce the chief points of his characterization of the four classes.I.Savages.—Their food consists of wild natural products (the fruits and roots of plants, and wild animals of all kinds). Most of them are, therefore, fishers or hunters. They are ignorant of agriculture and the breeding of cattle. They live isolated lives in families or scattered in small groups, and have no fixed home. The lowest and oldest savages come very close to the anthropoid apes from which they have descended, in bodily structure and habits. We may distinguish three orders in this class—the lower, middle, and higher savages.A.Lower savages, approaching nearest to the ape, pygmies of small stature, four to four and a half feet high (rarely four and three-quarters); the women sometimes only three to three and a half feet. They are woolly haired and flat-nosed, of a black or dark brown color, with pointed belly, thin and short legs. They have no homes, and live in forests and caverns, and partly on trees; wander about in small families of ten to forty persons; quite naked, or with just a trace of some primitive garment. Of the lower races now livingwe must put in this class the Veddahs of Ceylon, the Semangs of the Malay Peninsula, the Negritos of the Philippines, the Andaman Islanders, the Kimos of Madagascar, the Akkas of Guinea, and the Bushmen of South Africa. Other scattered remnants of these ancient negroid dwarfs, which approach closely to the anthropoid apes, still live in various parts of the primitive forests of the Sunda Islands (Borneo, Sumatra, Celebes).The value of the life of these lower savages is like that of the anthropoid apes, or very little higher. All recent travellers who have carefully observed them in their native lands, and studied their bodily structure and psychic life, agree in this opinion. Compare the thorough treatment of the Veddahs of Ceylon in the work of the brothers Sarasin (of which I have given a summary in myTravels in Ceylon). Their only interests are food and reproduction, in the same simple form in which we find these among the anthropoid apes (cf.chapters xv. and xxiii. of myAnthropogeny). Our own ancestors were probably much the same ten thousand or more years ago. On the strength of fossil remains of Pleistocene men Julius Kollmann has shown it to be very probable that similar dwarf races (with an average height of four and a half feet) inhabited Europe at that time.B.Middle savages, somewhat larger and less apelike than the preceding, averaging five to five and a half feet in height. Their homes are rock caverns and shelters from the wind and rain. Though they have shirts and other rudiments of clothing, both sexes generally go naked; they have primitive weapons of wood and stone and rudely fashioned boats, wander in troops of fifty to two hundred, and have no social organization; certain races, however, have laws. To this group belong the Australian negroes and Tasmanians,the Ainos of Japan, the Hottentots, Fuegians, Macas, and some of the forest races of Brazil. The value of their life is very little superior to that of the preceding order.C.Higher savages, mostly of average human height (smaller in colder regions), having always simple dwellings (generally of skins or the bark of trees). They have always primitive clothing, and good weapons of stone, bronze, or copper. They wander in troops of one hundred to five hundred, led by prominent but not ruling princes, and exhibiting rudimentary differences of rank. The method of life is determined by hereditary customs. To this group belong many of the primitive inhabitants of India (Todas, Nagas, Curumbas, etc.), the Nicobar Islanders, the Samoyeds, and Kamtschadals; in Africa, the negroes of Damara; and most of the Indian tribes of North and South America. Their life is higher than that of the pithecoid lower and middle savages, but less than that of the barbarians.II.Barbarians or Semi-savages.—The greater part of their food consists of natural products, which they secure with some foresight; hence they have developed agriculture and pasture to a greater or less extent. The division of labor is slight, each family supplying its own wants. As a rule, a stock of food is provided for the whole year. As a result of this, art begins to develop. They have generally fixed dwellings.A.Lower Barbarians. Dwellings: Simple huts, generally grouped into villages and surrounded with plantations. Clothing worn regularly, but very simple: the men often naked in hot climates or with shirt. Pottery and cooking utensils, tools of stone, wood, or bone. Rudiments of commerce by exchange. Groups of one thousand to five thousand persons able to form larger communities; distinctions of rank and warfare. Princes rule according to traditional laws. Of this groupwe have in Asia many of the aboriginal inhabitants of India (Mundas, Khonds, Paharias, Bheels, etc.), the Dyaks of Borneo, the Battaks of Sumatra, Tunguses, Kirgises, etc.; in Africa the Kaffirs, Bechuanas, and Basutos; in Australasia the aborigines of New Guinea, New Caledonia, New Hebrides, New Zealand, etc.; and in America the Iroquois and Thlinkets, and the inhabitants of Nicaragua and Guatemala.B.Middle barbarians. Dwellings good and durable, generally of wood, roofed with cane or straw, forming fine towns. Clothing general, though nudity is not considered immoral. Pottery, weaving, and metal-work pretty well developed. Commerce in regular markets, with the use of money. States ruled by kings in accordance with traditional laws, fixed distinctions of rank, communities up to one hundred thousand persons. To these belong in Asia the Calmucks; in Africa many negro races (Ashantis, Fantis, Fellahs, Shilluks, Mombuttus, Owampos, etc.); in Polynesia the inhabitants of the Fiji, Tonga, Samoa, and Markesas islands. In Europe the Lapps belonged to this class two hundred years ago, the ancient Germans two thousand years ago, the Romans before Numa, and the Greeks of the Homeric period.C.Higher barbarians. Dwellings, usually solid stone buildings. Clothing obligatory, weaving habitual occupation of the women, metal-work far advanced, tools generally of iron. Restricted commerce, with minted money, no rudder-ships. Crude judicature in fixed courts; rudimentary writing. Masses of people, with progressive division of labor and hereditary distinctions of rank, sometimes reaching half a million souls, under an autonomous ruler. To this class belong in Asia most of the Malays (in the large Sunda Islands and the peninsula of Malacca), and the nomadic races of Tartars, Arabs, etc.; in Polynesia the islanders of Tahiti andHawaii; in Africa the Somalis and Abyssinians, and the inhabitants of Zanzibar and Madagascar. Of the historic peoples of antiquity we have the Greeks of the time of Solon, the Romans at the beginning of the republic, the Jews under the Judges, the Anglo-Saxons of the Heptarchy, and the Mexicans and Peruvians at the time of the Spanish invasion.III.Civilized Races.—Food and complex vital needs are easily satisfied on account of the advanced division of labor and improvement of instruments. Art and science are consequently developed more and more. The increasing specialization brings about a great elaboration of individual functions, and at the same time a great strengthening of the whole body politic, as there is complete mutual dependence. The citizens see that they must submit to the laws of the state.A.Lower civilized races. Towns with stone walls; vast architectural works in stone; use of the plough in agriculture. War is intrusted to a particular class. Writing firmly established, primitive law-books, fixed courts. Literature begins to develop. To this group belong in Asia the inhabitants of Thibet, Bhutan, Nepaul, Laos, Annam, Korea, Manchuria, and the settled Arabs and Turcomans; in Africa the Algerians, Tunisians, Moors, Kabyles, Tuaregs, etc. Of historical races we have the ancient Egyptians, Phœnicians, Assyrians, Babylonians, Carthaginians, the Greeks after Marathon, the Romans of the time of Hannibal, and the English under the Norman kings.B.Middle civilized races. Beautiful temples and palaces, built of stone and brick. Windows come into use, and sailing-ships. Commerce expands. Writing and written books are general; the literary instruction of the young is attended to. Militarism is further developed; so are legislation and advocacy. Of these we have in Asia the Persians, Afghans, Birmans, andSiamese; in Europe the Finns and Magyars of the eighteenth century. Of historical peoples we must count among them the Greeks of the age of Pericles, the Romans of the later republic, the Jews under the Macedonian rule, France under the first Capets, and England under the Plantagenets.C.Higher civilized races. Stone houses general; streets paved; chimneys, canals, water and wind mills. Beginnings of scientific navigation and warfare. Writing general, written books widely distributed, literature esteemed. The highly centralized state embraces communities of ten millions or more. Fixed and written codes of law are officially promulgated and applied by courts to particular cases. Numbers of government officials have settled rank. To this group belong in Asia the Chinese, Japanese, and Hindoos; also the Turks and the various republics of South America, etc. In history we have the Romans of the empire, and the Italians, French, English, and Germans of the fifteenth century.IV.Cultivated Races.—Food and other needs are artificially supplied with the greatest ease and in abundance, human labor being replaced by natural forces. The social organization grows and facilitates the play of all the social forces, and man obtains a great freedom to cultivate his mental and æsthetic qualities. Printing is in general use, the education of the young one of the first duties. War becomes less important; rank and fame depend less on military bravery than on mental superiority. Legislation is influenced by representatives of the people. Art and science are increasingly promoted by state aid.Alexander Sutherland distinguishes three stages of development—the lower, middle, and higher—in the fourth as well as in the preceding classes. To the first stage he assigns "the leading nations of Europe andtheir offshoots, such as the United States of North America." For the second stage—middle cultured races—he gives a programme that may be carried out in three or four hundred years' time, with this definition: "All men are well fed and housed; war is universally condemned, but breaks out now and again. Small armies and fleets of all the nations co-operate as a sort of international police; commercial and industrial life are directed according to the moral precepts of sympathy; culture is general; crime and punishment rare." Of the third and highest stage Sutherland merely says, "Too bold a subject for prophecy, that may not come for one thousand to two thousand years yet." This division seems to me too vague and unsatisfactory, in the sense that it does not properly emphasize the civilization of the nineteenth century in contrast with all preceding stages. It would be better to distinguishprovisionallythe following stages in modern civilization: first, sixteenth to eighteenth century; second, nineteenth century; and third, twentieth century and the future.A.Lower cultured races (Europe, sixteenth to eighteenth century). At the commencement of this period, the first half of the sixteenth century, we notice the preparatory movements to the full growth of mental life which was to achieve such great results in the following periods: 1. The cosmic system of Copernicus (1543) maintained by Galileo (1592). 2. The discovery of America by Columbus (1492) and of the East Indies by Vasco da Gama (1498), the first circumnavigation of the earth by Magellan (1520) and the evidence it afforded of the rotundity of the earth. 3. The liberation of the mind of Europe from the papal yoke by Martin Luther (1517) and the repulse of the prevailing superstition by the spread of the Reformation. 4. The new impulse to scientific investigation independently ofscholasticism and the Church and of the philosophy of Aristotle; the founding of empirical science by Francis Bacon (1620). 5. The spread of scientific knowledge by the press (Gutenberg, 1450) and wood-engraving. The way was prepared for modern civilization by these and other advances in the sixteenth century, and it quickly arose above the barbaric level of the Middle Ages. However, it was confined at first within narrow limits, as the reactionary civilization of the Middle Ages was still powerful in political and social life, and the struggle against superstition and unreason made slow progress. The French Revolution (1792) at last gave a great impetus in practical directions.B.Middle cultured races. This name may be given to the leading nations of Europe and North America in the nineteenth century. We may illustrate in the following achievements the great advance which this "century of science" made as compared with all preceding ages: 1. Deepening, experimental grounding, and general spread of a knowledge of nature; independent establishment of many new branches of science; founding of the cell-theory (1838), the law of energy (1845), and the theory of evolution (1859). 2. Practical and comprehensive application of this theoretical science to all branches of art and industry. Especially 3. The overcoming of time and space by the extraordinary speed of transit (steamboats, railways, telegraphs, electrotechnics). 4. Construction of the monistic and realistic philosophy, in opposition to the prevailing dualistic and mystical views. 5. Increasing influence of rational scientific instruction and abandonment of the religious fiction of the Churches. 6. Increasing self-consciousness of the nations on account of having a share in government and legislation; extinction of the belief in the divine right of rulers. New distinction of classes. However, these great advances, to which we children ofthe nineteenth century may point with pride, are far from being universal; they are struggling daily with reactionary views and powers in Church and state, with militarism, and with ancient and venerable immorality of every kind.C.The higher culture which we are just beginning to glimpse will set itself the task of creating as happy and contented a life as possible for all men. A perfect ethic, free from all religious dogma and based on a clear knowledge of natural law, will be found in the golden rule, "Love thy neighbor as thyself." Reason tells us that a perfect state must provide the greatest possible happiness for every individual that belongs to it. The adjustment of a rational balance between egoism and altruism is the aim of our monistic ethics. Many barbaric customs that are still regarded as necessary—war, duelling, ecclesiastical power, etc.—will be abolished. Legal decisions will suffice to settle the quarrels of nations, as they now do of individuals. The chief interest of the state will be, not the formation of as strong a military force as possible, but the best possible instruction of its young, with special attention to art and science. The improvement of technical methods, owing to new discoveries in physics and chemistry, will bring greater satisfaction of our needs of life. The artificial production of albumin will provide plenty of food for all. A rational reform of the marriage relations will increase the happiness of family life.The darker sides of modern life, of which we are all more or less sensitive, have been laid bare by Max Nordau in hisConventional Lies of Civilization. They will be greatly altered if reason is permitted to have its way in practical life, and the present evil customs, based on antiquated dogmas, are suppressed. But, in spite of all these shades, the luminous features of modern civilization are so great that we look to the future with hopeand confidence. We need only glance back half a century, and compare life to-day with what it was then, in order to realize the progress made. If we regard the modern state as an elaborate organism (a "social individual of the first order"), and compare its citizens to the cells of a higher tissue-animal, the difference between the state of to-day and the crudest family groups of savages is not less than that between a higher metazoon (such as a vertebrate) and a cœnobium of protozoa. The progressive division of labor, on the one hand, and the centralization of society, on the other, prepare the social body for higher functions than in isolation, and proportionately increase the worth of its life. To see this more clearly, let us compare the personal and the social value of life in the five chief fields of vital activity—nutrition, reproduction, movement, sensation, and mental life.The first need of the individual organism, self-maintenance, is met in a much more perfect manner in the modern state than it was formerly. The savage is satisfied with the raw products of nature—with hunting, fishing, and the gathering of roots and fruits. Agriculture and pasturage come later. Many stages of barbarism and lower civilization must be passed before the conditions of feeding, housing, and clothing provide a secure and comfortable existence for man, and permit the addition of æsthetic and intellectual interests to the indispensable search for food.The feeding and condition of the social body as a whole have been improved by modern civilization, just as in the case of the individual. The progress of chemistry and agriculture has enabled us to produce food in larger quantities. The ease and rapidity of transfer allow it to be distributed over the whole earth. Scientific medicine and hygiene have discovered many means of diminishing the dangers of disease and preventing itsoccurrence. By means of public baths, gymnasiums, popular restaurants, public gardens, etc., greater care is taken of the health of the community. The arrangement of modern houses and their heating and lighting have been immensely improved. Modern social politics strives more and more to extend these benefits of civilization to the lower classes. Philanthropic societies are busy supplying the material and spiritual wants of various classes of sufferers. It is true there is still a broad margin for the improvement of the national well-being. But, on the whole, it cannot be denied that the provision of food in the modern state is an immense advance upon that of the Middle Ages and of the barbaric period.The great value of modern civilization and its vast progress beyond the condition of the savage is seen in no branch of physiology so conspicuously as in the wonderful process of reproduction and the maintenance of the species. In most savages and barbarians the satisfaction of their powerful sexual impulse is at the same low stage as in the ape and other mammals. The woman is merely an object of lust to the man, or even a slave without rights, bought and exchanged like all other property. Improvement is slow and gradual in the value of this property, until it reaches a high guarantee of permanency in the formal marriage. The family life proves a source of higher and finer enjoyment for both parties. The position of woman advances with civilization; her rights obtain further recognition, and in addition to sensual love the psychic relation of man and wife begins to develop. The common concern for the proper care and education of the children, which we find to an extent even in the case of many animals, leads to the further development of family life and the founding of the school. With the advent of a higher stage of civilization begins the refinement of sexual love, which finds its highest satisfaction, not in the momentarygratification of the sex-impulse, but in the spiritual relation of the sexes and their constant and intimate intercourse. The beautiful then unites with the good and the true to form a harmonious trinity. Hence love has been for thousands of years the chief source of the æsthetic uplifting of man in every respect; the arts—poetry, music, painting, and sculpture—have drawn inexhaustively from this source. However, for the individual civilized human being this higher love is of value, not only because it satisfies the natural and irresistible sex-impulse in its noblest form, but also because the mutual influence of the sexes, their complementary qualities and their common enjoyment of the highest ideal good, has a great effect upon individual character. A good and happy marriage—which is not very common to-day—ought to be regarded, both psychologically and physiologically, as one of the most important ends of life by every individual of the higher nations.As a pure marriage is the best form of family life and the most solid foundation of the state, its high social value is at once evident. The attraction and mutual devotion of the sexes fulfils in the highest degree the ethical golden rule—the balance of egoism and altruism. As Fritz Schultze very truly says in hisComparative PsychologyWe must not seek the causes of this altruism in the transcendental region of the supernatural, or in any metaphysical abstraction, but must go back to the very real and natural qualities of the organic being—and then there can be no question that the organic sex-impulse, at once physical and psychical is the first and enduring source of all love, however spiritual, and of all real ethical and sympathetic feelings and the morality founded thereon. There are two primitive instincts in all organisms: that of self-maintenance and that of the maintenance of the species. The one is the strong impulse of egoism, the other the spring of altruism: from the one come all unfriendly and from the other all friendly feelings. Every being seeksfirst to nourish and protect itself in virtue of its instinct of self-maintenance. But soon the magic of the instinct for the maintenance of the species works in it; it feels the sex-impulse, and thinks it is only satisfying its egoistic lust in yielding to it. In this it is wrong; it is not really serving itself, but the whole, the species, the genus. The ardor of love burns in it; and however sensual this love is at first, the new feeling is undeniably a feeling of belonging to another and of mutual consideration, looking not only to itself, but to another; not only to its own good, but to that of another, and finding its own good only in that of the other. And though this feeling at first only unites the two parents, it enlarges when children enter into life, and is extended to them in the form of parental love. Thus, out of the sex-impulse of the maintenance of the species, with its strong physical and psychic roots, is developed the love of spouses, of parents, of children, and of neighbor. Disinterested egoism goes even to the extent of sacrificing its own life for its young; in this organic and natural family love, and in the sense of the family that comes of it, we find the roots of all sympathetic and really ethical altruistic feelings; from this it widens out to larger spheres. Hence, the family is rightly held to be the chief source of all real moral feeling and life, not only in the human, but also in the animal world.The further ennoblement of family life in the advance of civilization will give fresh proofs of the truth of this appreciation.We now turn to consider the advantages that modern civilization offers in the way of movement in contrast to the simple methods of locomotion of the savage. We may point out first that the earliest men, like their ancestors, the anthropoid apes, lived in trees, and only gradually began to run on the ground. Some of the higher savages began to use the horse for riding and to tame it. Many inhabitants of the coast or islands began at an early period to make boats. Later the barbaric tribes invented the wagon, and much later again streets were paved and vehicles improved by civilized races. But the nineteenth century brought the invaluable means of rapid and convenient travelling by meansof steamboats and railways. The whole problem of transit was revolutionized, and in the last few decades further vast changes have been made owing to the advance of electricity. Modern ideas of time and space are quite different from those of our parents sixty years ago, or our grandparents ninety years ago. In our expresses we cover in an hour a stretch of country that the mail-coach took five times and the foot-passenger ten times as long to cover. As the experiments with the Berlin electric railway have lately shown, we can now travel two hundred kilometres in an hour. The journey from Europe to India now takes three weeks, whereas the earlier sailing-vessel took as many months. The immense saving of time that we make is equivalent to a lengthening of our own life. This applies also to the more rapid transit provided by balloons, automobiles, bicycles, etc. It is easy to estimate the value of these improvements; but it is only fully appreciated by those who have lived long in an uncivilized country without roads or among savages whose legs are their only means of locomotion.
The vitalist and teleological idea of an internal principle of evolution, that determines the origin of animal and plant species independently of the environment and its conditions, is not only found in the "mechanical-physiological" theory of Nägeli, but also in several other attempts to explain the agencies of the transformation of species. All these efforts are welcomed by the academic philosophers with their Kantist dualism (mechanicism on the right, teleology on the left), and who are particularly anxious to save the supernatural element, Reinke's "cosmic intelligence," or the wisdom of the Creator, or the divine creative thought. All these dualistic and teleological efforts have the same fault: they overlook, or fail to appreciate properly, the immense influence of the environment on the shaping and modification of organisms. When, moreover, they deny progressive heredity and its connection with functional adaptation, they lose the chief factor in transformation. This applies also to the theory of germ-plasm.
The desire to penetrate deeper into the mysterious processes that take place in the plasm in the physiological activities of heredity and adaptation has led to the formulation of a number of molecular theories. The chief of these are the pangenesis theory of Darwin (1878), my own perigenesis theory (1876), the idioplasm theory of Nägeli (1884), the germ-plasm theory of Weismann (1885), the mutation theory of De Bries, etc. As I havealready dealt with these in the sixth chapter (as well as in the ninth chapter of theHistory of Creation), I may refer the reader thereto. None of these or similar attempts has completely solved the very difficult problems in question, and none of them has been generally received. There is, however, one of them that we must consider more closely, because it is not only regarded by many biologists as the greatest advance of the theory of selection since Darwin, but it also touches the roots of several of the chief problems of biogeny. I mean the much-discussed germ-plasm theory of August Weismann (of Freiburg), one of our most distinguished zoologists. He has not only promoted the theory of descent by his many writings during the last thirty years, but has also put in its proper light the great importance and entire accuracy of the theory of selection. But, in his efforts to provide a molecular-physiological basis for it, he has proceeded by way of metaphysical speculation to frame a quite untenable theory of the plasm. While fully recognizing the ability and consistency and the able treatment which Weismann has shown, I am compelled once more to dissent from him. His ideas have recently been completely refuted by Max Kassowitz (1902) in hisGeneral Biology, and Ludwig Plate in the work I mentioned on the Darwinian principle of selection. We need not go into the details of the complicated hypothesis as to the molecular structure of the plasm which Weismann has framed in support of his theory of heredity—his theory of biophora, determinants, ideas, etc.—because they have no theoretical basis and are of no practical use. But we must pass some criticism on one of their chief consequences. In the interest of his complicated hypotheses, Weismann denies one of Lamarck's most important principles of transmutation—namely, the inheritance of acquired characters.
When I made the first attempt in 1866 to formulatethe phenomena of heredity and adaptation in definite laws and arrange these in series, I drew a distinction between conservative and progressive heredity (chapter ix.,History of Creation). Conservative heredity, or the inheritance of inherited characters, transmits to posterity the morphological and physiological features which each individual has received from his parents. Progressive heredity, or the inheritance of acquired characters, transmits to offspring a part of those features which were acquired by the parents in the course of their individual lives. The chief of these are the characters that are caused by the activity of the organs themselves. Increase in the use of the organs causes a greater access of nourishment and promotes their growth; decrease in the exercise of organs has the contrary effect. We have examples at hand in the modification of the muscles or the eyes, the action of the hand or throat in painting or singing, and so on. In these and all the arts the rule is: Practice makes perfect. But this applies almost universally to the physiological activity of the plasm, even its highest and most astounding function—thought; the memory and reasoning capacity of the phronema are improved by constant exercise of the cells which compose this organ, just as we find in the case of the hands and the senses.
Lamarck recognized the great morphological significance of this physiological use of the organs, and did not doubt that the modification caused was transmitted to offspring to a certain extent. When I dealt with this correlation of direct adaptation and progressive heredity in 1866, I laid special stress on the "law of cumulative adaptation" (General Morphology, ii., p. 208). "All organisms undergo important and permanent (chemical, morphological, and physiological) changes when acted on by a change in its life-conditions, slight in itself, but continuing for a long time or being frequently repeated."At the same time I pointed out that in this case two groups of phenomena are closely connected which are often separated—namely, cumulative heredity: firstlyexternal, by the action of the external conditions (food, climate, environment, etc.), and secondlyinternal, by the reaction of the organism, the influence of internal conditions (habit, use and disuse of organs, etc.). The action of outer influences (light, heat, electricity, pressure, etc.) not only causes a reaction of the organism affected (energy of movement, sensation, chemosis, etc.), but it has an especial effect as a trophic stimulus on its nutrition and growth. The latter element has been particularly studied by Wilhelm Roux; his functional adaptation (1881) coincides with my cumulative adaptation, the close relation of which to correlative adaptation I had pointed out in 1866. Plate has recently given this "definitely directed variation" the name of ectogenetic orthogenesis, or, briefly, ectogenesis.
The controversy about progressive heredity still continues here and there. Weismann completely denies it, because he cannot bring it into harmony with his germ-plasm theory, and because he thinks there are no experimental proofs in support of it. A number of able biologists agree with him, led away by his brilliant argumentation. However, many of them foolishly lay great stress on experiments in heredity which prove nothing; for instance, the fact that the offspring of a mammal that has had its tail cut off do not inherit the feature. A number of recent observations seem to prove that in a few cases even defects of this sort (when they have caused profound and lasting disease of the part affected) may be transmitted to offspring. However, as far as the formation of new species is concerned, the fact is of no consequence; in this it is a question of cumulative or functional adaptation. Experimental proofs of this are difficult to find, if one wants a strict demonstrationof the type of physical experiments; the biological conditions are generally too complicated and offer too many weak points to rigorous criticism. The beautiful experiments of Standfuss and C. Fisher (Zurich) have shown that changes in the environment (such as temperature or food) can cause striking modifications that are transmitted to offspring. In any case, there are plenty of luminous proofs of progressive heredity in the vast arsenal of morphology, comparative anatomy, and ontogeny.
Comparative anatomy affords a number of most valuable arguments for other phylogenetic questions as well as progressive heredity; and the same may be said of comparative anatomy and comparative ontogeny. I have collected and illustrated a good many of these proofs in the new edition of myAnthropogeny. However, in order to understand and appreciate them aright, the reader must have some acquaintance with the methods of critical comparison. This means not only an extensive knowledge of anatomy, ontogeny, and classification, but also practice in morphological thinking and reasoning. Many of our modern biologists lack these qualifications, especially those "exact" observers who erroneously imagine they can understand vast groups of phenomena by accurate description of detailed microscopic structures, etc. Many distinguished cytologists, histologists, and embryologists have completely lost the larger view of their work by absorption in these details. They even reject some of the fundamental ideas of comparative anatomy, such as the distinction between homology and analogy; Wilhelm His, for instance, declared that these "academic ideas" are "unreliable tools." On the other hand, physiological experiments ought to contribute to the solution of morphological problems, and of these they can say nothing. To show the incalculable value of comparative anatomy for phylogeny,I need only point to one of its most successful departments, the skeleton of the vertebrates, the comparison of the various forms of the skull, the vertebral column, the limbs, etc. It is not in vain that for more than a hundred years gifted scientists, from Goethe and Cuvier to Huxley and Gegenbaur, have devoted years of laborious research to the methodical comparison of these similar yet dissimilar forms. They have been rewarded by the discovery of the common laws of structure, which can only be explained in the sense of modern evolution by descent from common ancestors.
We have a striking example of this in the limbs of mammals, which, with the same internal skeletal structure, show a very great variety in outer form—the slender bones of the running carnivora and ungulates, the oar-bones of the whale and seal, the shovel-bones of the mole and hypudæus, the wings of the bat, the climbing bones of the ape, and the differentiated limbs of the human body. All these different skeletal forms have descended from the same common stem-form of the oldest Triassic mammals; their various forms and structures are adapted in scores of ways to different functions; but they risethroughthese functions, and all these functional adaptations can only be understood by progressive heredity. The theory of germ-plasm gives no causal explanation whatever of them.
The majority of recent biologists are of opinion that of the two chief constituents of the nucleated cell the cytoplasm of the cell-body discharges the function of nutrition and adaptation, while the caryoplasm of the nucleus accomplishes reproduction and heredity. I first advanced this view in the ninth chapter of theGeneral Morphology(in 1866); and it was afterwards solidly and empirically established by the excellent investigations of Eduard Strasburger, the brothers Oscar and Richard Hertwig, and others. The elaborate finer structures which theseobservers discovered in cell-division led to the theory that the colorable part of the nucleus, chromatin, is the real hereditary matter, or the material substratum of the energy of heredity. Weismann added the theory that this germ-plasm lives quite separately from the other substances in the cell, and that the latter (the soma-plasm) cannot transmit to the germ-plasm the characters it has acquired by adaptation. It is on the strength of this theory that he opposes progressive heredity. The representatives of the latter (including myself) do not accept this absolute separation of germ-plasm from body-plasm; we believe that even in the process of cell-division in the unicellular organism there is partial blending of the two kinds of plasm (caryolysis), and that in the multicellular organism of the histona also the harmonious connection of all the cells by their plasma-fibres makes it possible enough for all the cells in the body to act on the germ-plasm of the germ-cells. Max Kassowitz has shown how we can explain this influence by the molecular structure of the plasm.
At the beginning of the twentieth century a new biological theory aroused a good deal of interest, and was welcomed by some as an experimental refutation of Darwin's theory of selection and by others as a valuable supplement to it. The distinguished botanist Hugo de Bries (of Amsterdam) gave an interesting lecture at the scientific congress at Hamburg in 1901 on "The Mutations and Mutation-periods in the Origin of Species." Supported by many years of experiments in selection and some ingenious speculations, he thinks he has discovered a new method of the transformation of species, an abrupt modification of the specific form at a bound, and so discredited Darwin's theory of their gradual change through long periods of time. In a large work onExperiments and Observations on the Origin of Species in the Plant Kingdom(1903), De Bries has endeavored todemonstrate the truth of his theory of mutation. The warm approval which it won from a number of eminent botanists, and especially vegetal physiologists, was not shared by zoologists. Of these Weismann, in hisLectures on the Theory of Descent(1902, ii. p. 358), and Plate in hisProblems of Species-formation(1903, p. 174), have dealt fully with the theory of mutation, and, while appreciating the interesting observations and experiments of De Bries, have rejected the theory he has built on them. As I share their opinion, I may refer the reader who is interested in these difficult problems to their works, and will restrict myself here to the following observations. The chief weakness of the theory of mutation of De Bries is on its logical side, in his dogmatic distinction between species and variety, mutation and variation. When he holds the constancy of species as a fundamental "fact of observation," we can only say that this (relative) permanence of species is very different in the different classes. In many classes (for instance, insects, birds, many orchids and graminea) we may examine thousands of specimens of a species without finding any individual differences; in other classes (such as sponges, corals, in the generarubusandhieracium) the variability is so great that classifiers hesitate to draw up fixed species. The marked difference between various forms of variability which De Bries alleges cannot be carried through; the fluctuating variations (which he takes to be unimportant) cannot be sharply distinguished from the abrupt mutations (from which new species are supposed to result at a bound). De Bries's mutations (which I distinguished in theGeneral Morphologyas "monstrous changes" from other kinds of variation) must not be confused with the paleontological mutations of Waagen (1869) and Scott (1894) which have the same name. The sudden and striking changes of habit which De Bries observed onlyin one single species ofœnotheravery rarely occur, and cannot be regarded as common beginnings of the formation of new species. It is a curious freak of chance that this species bears the nameœnothera Lamarckiana; the views of the great Lamarck on the powerful influence of functional adaptation have not been refuted by De Bries. It must be carefully noted, in fact, that De Bries is firmly convinced of the truth of Lamarck's theory of descent, like all competent modern biologists. This must be well understood, because recent metaphysicians see in the supposed refutation of Darwinism the death of the whole theory of transformism and evolution. When they appeal in this sense to its most virulent opponents, Dennert, Driesch, and Fleischmann, we may remind them that the curious sermons of these minor sophists are no longer noticed by any competent and informed scientist.
Not only in the brilliant speculations of De Bries and Nägeli, but also in many other botanical works that have lately attempted to advance the theory of descent, we find a striking difference from the prevailing views of zoologists in the treatment of a number of general biological problems. This difference is, of course, not due to a disproportion of ability in the two great and neighboring camps of biology, but to the differences in the phenomena that we observe in plant life on the one hand and animal life on the other. It must be noted particularly that the organism of the higher animals (including our own) is much more elaborately differentiated in its various organs and much more exposed to our direct experience than that of the higher plants. The chief properties and activities of our muscles, skeleton, nerves, and sense-organs, are understood at once in comparative anatomy and physiology. The study of the corresponding phenomena in the bodies of the higher plants is much more difficult. The features ofthe innumerable elementary organs in the cell-monarchy of the animal body are much more intricate, yet at the same time much more intelligible, than those of the cell-republic of the higher plant-body. Thus the phylogeny of the plants encounters much greater difficulties than that of the animals; the embryology of the former says much less in detail than that of the latter. We can understand, therefore, why the biogenetic law is not so generally recognized by botanists as by zoologists. Paleontology, which provides such valuable fossil material for many groups of the animal kingdom that we can more or less correctly draw up their ancestral tree on the strength of this, gives us very little for most groups of the plant kingdom. On the other hand, the large and sharply demarcated plant-cell, with its various organella, is much more valuable in connection with many problems than the tiny animal-cell. For many physiological purposes, in fact, the higher plant body is more accessible to exact physical and chemical research than the higher animal body. The antithesis is less in the kingdom of the protists, as the difference between animal and vegetal life is mostly confined to difference of metabolism, and finally disappears altogether in the province of the unicellular forms of life. Hence, for a clear and impartial treatment of the great problems of biology, and especially of phylogeny, it is imperative to have a knowledge of both zoological and botanical investigation. The two great founders of the theory of descent—Lamarck and Darwin—were able to penetrate so deeply into the mysteries of organic life and its development because they had extensive attainments both in botany and zoology.
Of the various tendencies that have recently made their appearance among zoologists and botanists in the discussion of the theory of descent, we frequently find Neo-Lamarckism and Neo-Darwinism distinguished asopposing schools. This opposition has no meaning unless we understand by it the alternatives of transformism—with or without the theory of selection. The one principle that distinguishes Darwinism proper from the older Lamarckism is the struggle for existence and the theory of selection based on it. It is quite wrong to make the test an acceptance or rejection of progressive heredity. Darwin was just as firmly convinced as Lamarck or myself of the great importance of the inheritance of acquired characters, and particularly of the inheritance of functional adaptations; he merely ascribed to it a more restricted sphere of influence than Lamarck. Weismann, however, denies progressive heredity altogether, and wants to trace everything to "the omnipotence of natural selection." If this view of Weismann and the theory of germ-plasm he has based on it are correct, he alone has the honor of founding a totally new (and in his opinion very fruitful) form of transformism. But it is quite wrong to describe this Weismannism as Neo-Darwinism, as frequently happens in England. It is just as wrong to call Nägeli, De Bries, and other modern biologists who reject selection Neo-Lamarckists.
If the theory of descent is right, as all competent biologists now admit, it puts on morphology the task of assigning approximately the origin of each living form. It must endeavor to explain the actual organization of each by its past, and to recognize the causes of its modification in the series of its ancestors. I made the first attempt to achieve this difficult task in founding stem-history or phylogeny as an independent historical science in my "General Evolution" (in the second volume of theGeneral Morphology). With it I associated as a second and equally sound part ontogeny; I understood by this the whole science of the development of the individual, both embryology and metamorphology. Ontogeny enjoys the privileges (especially in the wayof certainty) of a purely descriptive science, when it confines itself to the faithful description of the directly observed facts, either the embryonic processes in the womb or the later metamorphic processes. The task of phylogeny is much more difficult, as it has to decipher long-past processes by means of imperfect evidence, and has to use its documents with the utmost prudence.
The three most valuable sources of evidence in phylogeny are paleontology, comparative anatomy, and ontogeny. Paleontology seems to be the most reliable source, as it gives us tangible facts in the fossils which bear witness to the succession of species in the long history of organic life. Unfortunately, our knowledge of the fossils is very scanty and often very imperfect. Hence the numerous gaps in its positive evidence have to be filled up by the results of two other sciences, comparative anatomy and ontogeny. I have dealt fully with this in myAnthropogeny. As I have also spoken of the general features of these phyletic evidences in the sixteenth chapter of theHistory of Creation, I need do no more here than repeat that it is necessary to make equal and discriminating use of all three classes of documents if we are to attain the aim of phylogeny correctly. Unfortunately, this necessitates a thorough knowledge of all three sciences, and this is very rare. Most embryologists neglect paleontology, most paleontologists embryology, while comparative anatomy, the most difficult part of morphology, involving most extensive knowledge and sound judgment, is neglected by both. Besides these three sources of phylogeny there is valuable proof afforded by every branch of biology, especially by chorology, œcology, physiology, and biochemistry.
Although there has been very extensive phylogenetic research during the last thirty years, and it has yielded a number of interesting results, many scientists still seemto look on them with a certain distrust; some contest their scientific value altogether, and say that they are nothing but airy and untenable speculations. This is especially the case with many physiologists who look upon experiment as the only exact method of investigation, and many embryologists who think their sole task is description. In view of these sceptical strictures, we may recall the history and the nature of geology. No one now questions the great importance and the various uses of this science, although in it there is no possibility of directly observing the historical processes as a rule. No scientist now doubts that the three vast successive formations of the Mesozoic Period—the Triassic, Jurassic, and Cretaceous—have been formed from sea-deposits (lime, sandstone, and clay), though no one was a witness to the actual formation; no one doubts to-day that the fossil skeletons of fishes and reptiles which we find in these groups are not mysterious freaks of nature, but the remains of extinct fishes and reptiles that lived on the earth during those millions of years long ago. And when comparative anatomy shows us the genealogical connection of these related forms, and phylogeny (with the aid of ontogeny) constructs their ancestral trees, their historical hypotheses are just as sound and reliable as those of geology; the only difference is that the latter are much simpler, and thus easier to construct. Phylogeny and geology are, in the nature of the case,historical sciences.
Hypotheses are necessary in phylogeny and geology, where the empirical evidence is incomplete, as in every other historical science. It is no detraction from the value of these to urge that they are sometimes weak and have to be replaced by better and stronger ones. A weak hypothesis is always better than none. We must, therefore, protest against the foolish dread of hypotheses which is urged against our phylogenetic methods by therepresentatives of the exact and descriptive sciences. This shrinking from hypotheses often hides a defective knowledge of other sciences, an incapacity for synthetic thought, and a feeble sense of causality. The delusions into which it leads many scientists may be seen from the fact that chemistry, for instance, is reckoned an "exact" science; yet no chemist has ever seen the atoms and molecules of compounds with which he is occupied daily, or the complicated relations on the assumption of which the whole of modern structural chemistry is based. All these hypotheses rest on inferences, not on direct observation.
I have, from the first, insisted on the close causal connection between ontogeny and phylogeny, ever since I distinguished these two parts of biogeny in the fifth book of theGeneral Morphology. I also laid stress on the mechanical character of these sciences, and endeavored to give a physiological explanation of their morphological phenomena. Until then embryology had been regarded as a purely descriptive science. Carl Ernst Baer, who had provided a solid foundation for it in his classicAnimal Embryology(1828), was convinced that all the phenomena of individual development might be reduced to the laws of growth; but he was quite unconscious of the real direction of this growth, its "purposiveness," the real causes of construction. The distinguished Würtzburg anatomist, Albert Kölliker, whoseManual of Human Embryology(1859) gave the first comprehensive treatment of the science from the cellular point of view, adhered, even in the fourth edition (1884), to the opinion that "the laws of the development of the organism are still completely unknown." In opposition to this generally received opinion, I endeavored, in 1866, to prove that Darwin had, by his improvement of the theory of descent, not only solved the phylogenetic problem of the origin of species,but, at the same time, given us the key to open the closed doors of embryology, and to learn the causes of the ontogenetic processes as well. I formulated this view in the twentieth chapter of theGeneral Morphology, in forty-four theses, of which I will quote only the following three: 1. The development of organisms is a physiological process, depending on mechanical causes, or physico-chemical movements. 40. Ontogenesis, or the development of the organic individual, is directly determined by phylogenesis, or the evolution of the organic stem (phylon) to which it belongs. 41. Ontogenesis is a brief and rapid recapitulation of phylogenesis, determined by the physiological functions of heredity and adaptation. The pith of my biogenetic principle is expressed in these and the remaining theses on the causal nexus of biontic and phyletic development. At the same time I make it quite clear that I reduce the physical process of ontogenesis, and also phylogenesis, to a pure mechanics of the plasm (in the sense of the critical philosophy).
The comprehensive fundamental law of organic development was briefly formulated by me in the fifth book of theGeneral Morphologyand in the tenth chapter of theHistory of Creation(developed more fully in the fourteenth chapter of the tenth edition, 1902). I afterwards sought to establish it securely in two different ways. In the first place, I proved in myStudies of the Gastræa Theory(1872-1877) that in all the tissue-animals, from the lowest sponges and polyps to the highest articulata and vertebrates, the multicellular organism develops from the same primitive embryonic form (thegastrula), and that this is the ontogenetic repetition, in virtue of heredity, of a corresponding stem-form (thegastræa). In the second place, I made the first attempt in myAnthropogeny(1874) to illustrate this recapitulation theory from the instance of our own human organism,by trying to explain the complex process of individual development, for the whole frame and every single part of it, by causal connection with the stem-history of our animal ancestors. In the latest edition of this monistic "ontogeny of man" I gave numbers of illustrations (thirty plates and five hundred engravings) of these intricate structures, and endeavored to make the subject still plainer by the addition of sixty genetic tables. I may refer the reader to this work,[10]and not dwell any further here on the biogenetic law, especially as one of my pupils, Heinrich Schmidt (of Jena), has recently described its biological significance and its earlier history and present position in a very clear and reliable little work (Haeckel's Biogenetic Law and its Critics). I will only add a word or two on the struggle that has taken place for thirty years over the complete or partial recognition of the biogenetic law, its empirical establishment, and its philosophic application.
In the very name, "fundamental law of biogeny," which I have given to my recapitulation theory, I claim that it is universal. Every organism, from the unicellular protists to the cryptogams and cœlenteria, and from these up to the flowering plants and vertebrates, reproduces in its individual development, in virtue of certain hereditary processes, a part of its ancestral history. The very word "recapitulation" implies a partial and abbreviated repetition of the course of the original phyletic development, determined by the "laws of heredity and adaptation." Heredity brings about the reproduction of certain evolutionary features; adaptation causes a modification of them by the conditions of the environment—a condensation, disturbance, or falsification. Hence I insisted from the first that the biogenetic law consists of two parts, one positive and palingeneticand the other restrictively negative and cenogenetic.Palingenesisreproduces a part of the original history of the stem;cenogenesisdisturbs or alters this picture in consequence of subsequent modifications of the original course of development. This distinction is most important, and cannot be too often repeated in view of the persistent misunderstanding of my opponents. It is overlooked by those who (like Plate and Steinmann) grant it only a partial validity, and by those who reject it altogether (like Keibel and Hensen). The embryologist Keibel is the most curious of these, as he has himself afforded a good many proofs of the biogenetic law in his careful descriptive-embryological works. But he has so little mastered it that he has never understood the distinction between palingenesis and cenogenesis.
It is especially unfortunate that one of our most distinguished embryologists, Oscar Hertwig, of Berlin, who provided a good deal of evidence in favor of the biogenetic law thirty years ago, has lately joined the opponents of it. His supposed "correction" or modification of it is, as Keibel has rightly said, a complete abandonment of it. Heinrich Schmidt has partly explained the causes of this change in his work on the biogenetic law. They are not unconnected with the psychological metamorphosis which Oscar Hertwig has undergone at Berlin. In the discourse on "The Development of Biology in the Nineteenth Century," which he delivered at the scientific congress at Aachen in 1900, he openly accepted the dualist principles of vitalism (although he says they are "just as unreliable as the chemico-physical conception of the opposing mechanical school"). The views which he has lately advanced on the worthlessness of Darwinism and the unreliability of phylogenetic hypotheses are diametrically opposed to the opinions he represented at Jena twenty-five years ago, and to those which hisbrother, Richard Hertwig, of Munich, has consistently maintained in his admirableManual of Zoology.
In opposition to the mechanical ontogeny which I formulated in 1866 and embodied in the biogenetic law, a number of other tendencies in embryology afterwards appeared, and, with the common title of "mechanical embryology," branched out in every direction. The chief of these to attract attention thirty years ago were the pseudo-mechanical theories of Wilhelm His, who has rendered great service to ontogeny by his accurate descriptions and faithful illustrations of vertebrate-embryos, but who has no idea of comparative morphology, and so has framed the most extraordinary theories about the nature of organic development. In hisStudy of the First Sketch of the Vertebrate-body(1868), and many later works, His endeavored to explain the complicated ontogenetic phenomena on direct and simple physical lines by reducing them to elasticity, bending, folding of the embryonic layers, etc., while explicitly rejecting the phylogenetic method; he says that this is "a mere by-way, and quite unnecessary for the explanation of the ontogenetic facts (as direct consequences of physiological principles of development)." As a matter of fact, nature rather plays the part of an ingenious tailor in His's pseudo-mechanical and tectogenetic speculations, as I have shown in the third chapter of theAnthropogeny. Hence they have been humorously called the "tailor theory." However, they misled a few embryologists by opening the way to a direct and purely mechanical explanation of the complex embryonic phenomena. Although they were at first much admired, and immediately afterwards abandoned, they have found a number of supporters lately in various branches of embryology.
The great success that modern experimental physiology achieved by its extensive employment of physicaland chemical experiments inspired a hope of attaining similar results in embryology by means of the same "exact" methods. But the application of them in this science is only possible to a slight extent on account of the great complexity of the historical processes and the impossibility of "exactly" determining historical matters. This is true of both branches of evolution, individual and phyletic. Experiments on the origin of species have very little value, as I said before; and this is generally true of embryological experiments also. However, the latter, especially careful experiments on the first stages of ontogenesis, have yielded some interesting results, particularly in regard to the physiology and pathology of the embryo at the earliest stages of development. TheArchiv für Entwickelungsmechanik, which is edited by the chief representative of this school, Wilhelm Roux, contains, besides these valuable inquiries, a good number of ontogenetic articles, which partly rely on and partly ignore the biogenetic law.
Psychology and biogeny have been up to the present regarded as the most difficult branches of biology for monistic explanation, and the strongest supports of dualistic vitalism. Both departments become accessible to monism and a mechanico-causal explanation by means of the biogenetic law. The close correlation which it establishes between individual and phyletic development, and which depends on the interaction of heredity and adaptation, makes it possible to explain both. In regard to the first, I formulated the following principle thirty years ago in my first study of the gastræa theory: "Phylogenesis is the mechanical cause of ontogenesis." This single principle clearly expresses the essence of our monistic conception of organic development:
In the future every student will have to declare himself for or against this principle, if in biogeny he is not content with a mere admiration of the wonderful phenomena, but desires to understandtheir significance. The principle also makes clear the wide gulf that separates the older teleological and dualistic morphology from the modern mechanical and monistic science. If the physiological functions of heredity and adaptation are proved to be the sole causes of organic construction, every kind of teleology, and of dualistic and metaphysical explanation, is excluded from the province of biogeny. The irreconcilable opposition between the leading principles of the two is clear. Either there is or is not a direct and causal connection between ontogeny and phylogeny. Either ontogenesis is a brief compendium of phylogenesis or it is not. Either epigenesis and descent—or pre-formation and creation.
In repeating these principles here, I would lay stress particularly on the fact that, in my opinion, our "mechanical biogeny" is one of the strongest supports of the monistic philosophy.
XVII
Changes of life—Aim of life—Progress of life—Historic aims—Historic waves—Value of life in classes and races of men—Psychology of uncivilized races—Savages—Barbarians—Civilized nations—Educated nations—Three stages of development (lower, middle, and higher) in each of the four classes—Individual and social value of civilized life in the five sections of nutrition, reproduction, movement, sensation, and mental life—Estimate of human life.
The value of human life is seen by us to-day, now that evolution is established, in quite a different light from fifty years ago. We are now accustomed to regard man as a natural being, the most highly developed natural being that we know. The same "eternal iron laws" that rule the evolution of the whole cosmos control our own life. Monism teaches that the universe really deserves its name, and is an all-embracing unified whole—whether we call it God or Nature. Monistic anthropology has now established the fact that man is but a tiny part of this vast whole, a placental mammal, developed from a branch of the order of primates in the later Tertiary Period. Hence, before we seek to estimate the value of man's life, we will cast a glance at the significance of organic life generally.
An impartial survey of the history of organic life on our planet teaches, first of all, that it is a process of constant change. Millions of animals and plants die every second, while other millions replace them; every individualhas his definite period of life, whether it lives only a few hours, like the one-day fly or the infusorium, or, like the Wellingtonia, the dragon-tree of Orotava, and many other giant trees, lives for thousands of years. Even the species, the collection of like individuals, is just as transitory, and so are the orders and classes that embrace numbers of species of animals and plants. Most species are confined to a single period of the organic history of the earth; few species or genera pass unchanged through several periods, and not a single one has lived in all the periods. Phylogeny, taking its stand on the facts of paleontology, teaches unequivocally that every specific living form has only existed a longer or shorter period in the course of the many (more than a hundred) million years which make up the history of organic life.
Every living being is an end to itself. On this point all unprejudiced thinkers are agreed, whether, like the teleologist, they believe in an entelechy or dominant as regulator of the vital mechanism, or whether they explain the origin of each special living form mechanically by selection and epigenesis. The older anthropistic idea, that animals and plants were created for man's use, and that the relations of organisms to each other were generally regulated by creative design, is no longer accepted in scientific circles. But it is just as true of the species as of the individual that it lives for itself, and looks above all to self-maintenance. Its existence and "end" are transitory. The progressive development of classes and stems leads slowly but surely to the formation of new species. Every special form of life—the individual as well as the species—is therefore merely a biological episode, a passing phenomenal form in the constant change of life. Man is no exception. "Nothing is constant but change," said the old maxim.
The historical succession of species and classes is, bothin the animal and the plant kingdom, accompanied by a slow and steady progress in organization. This is directly and positively taught by paleontology; its creation-medals, the fossils, are unequivocal and irrefutable witnesses to this phylogenetic advance. I have dealt with the subject in myHistory of Creation, and at the same time shown that both the progressive improvement and the increasing variety of the species can be explained mechanically as necessary consequences of selection. There was no need of a conscious Creator or a transcendental purposiveness to effect this. Scientific and thorough proof of this will be found in the three volumes of mySystematic Phylogeny(1894). I need only refer briefly to the two conspicuous examples we have in the stem-history of the tissue-plants and that of the vertebrates. Of the metaphyta the ferns are the chief groups in the Paleozoic, the gymnosperms in the Mesozoic, and the angiosperms in the Cenozoic age. Of the vertebrates only fishes are found in the Silurian age, dipneusta only begin in the Devonian, and the first mammals are in the Triassic.
A number of false teleological conclusions have been drawn from these facts of progressive modification of forms, as they are given in paleontology. The latest and most developed form of each stem was taken to be the preconceived aim of the series, and its imperfect predecessors were conceived as preparatory stages to the attainment of this aim. It was like the conduct of many historians, who, when a particular race or state has reached a high rank in civilization as a result of its natural endowments and favorable conditions of development, hail it as a "chosen people," and regard its imperfect earlier condition as a deliberately conceived preparatory stage. In point of fact, these evolutionary stages were bound to proceed according as the internal structure (given by heredity) and the outer conditions(provoking adaptation) determined. We cannot admit any conscious direction to a certain end, either in the form of theistic predestination or pantheistic finality. For this we must substitute a simple mechanical causality in the sense of psycho-mechanical monism or hylozoism.
Although the stem-history of plants and animals, like the history of humanity, shows a progressive advance taken as a whole, we find a good deal of vacillation in detail. These historical waves are wholly irregular; in periods of decay the hollows of the waves often persist for a long time, and are then succeeded by a fresh rise to the crest of another wave. New and rapidly advancing groups come to take the place of the old decaying groups, bringing with them a higher stage of organization. Thus, for instance, the ferns of to-day are only a feeble survival of the huge and varied pteridophyta that formed the most conspicuous part of the paleozoic forests in the Devonian and Carboniferous periods; they were ousted in the Secondary Period by their gymnosperm descendants (cycadea and conifers), and these, again, in the Tertiary Period by the angiosperm flowering plants. So among the terrestrial reptiles the modern tortoises, serpents, crocodiles, and lizards are only a feeble remnant of the enormous reptile-fauna that dominated the Secondary Period, the colossal dinosauri, pterosauri, ichtyosauri, and plesiosauri. They were replaced in the Tertiary Period by the smaller but more powerful mammals. In the history of civilization the Middle Ages form a deep valley between the crests of the waves of classical antiquity and modern culture.
These few examples suffice to show that the various classes and orders of living things have a very different value when compared with each other. In regard to their intrinsic aim, self-maintenance, it is true that all organisms are on a level, but in their relations to other living things and to nature as a whole they are of veryunequal value. Not only may larger animals and plants retain domination for a long time in virtue of their special use or superior force and mass, but small ones may prevail owing to their power of inflicting injury (bacteria, fungi, parasites, etc.). In the same way the value of the various races and nations is very unequal in human history. A small country like Greece has almost dominated the mental life of Europe for more than two thousand years in virtue of its superior culture. On the other hand, the various tribes of American Indians have, it is true, developed a partial civilization in some parts (Peru and Central America); but, on the whole, they have proved incapable of advancing.
Though the great differences in the mental life and the civilization of the higher and lower races are generally known, they are, as a rule, undervalued, and so the value of life at the different levels is falsely estimated. It is civilization and the fuller development of the mind that makes civilization possible, that raise man so much above the other animals, even his nearest animal relatives, the mammals. But this is, as a rule, peculiar to the higher races, and is found only in a very imperfect form or not at all among the lower. These lower races (such as the Veddahs or Australian negroes) are psychologically nearer to the mammals (apes or dogs) than to civilized Europeans; we must, therefore, assign a totally different value to their lives. The views on the subject of European nations which have large colonies in the tropics, and have been in touch with the natives for centuries, are very realistic, and quite different from the ideas that prevail in Germany. Our idealistic notions, strictly regulated by our academic wisdom and forced by our metaphysicians into the system of their abstract ideal-man, do not at all tally with the facts. Hence we can explain many of the errors of the idealistic philosophy and many of the practical mistakes that havebeen made in the recently acquired German colonies; these would have been avoided if we had had a better knowledge of the low psychic life of the natives (cf.the writings of Gobineau and Lubbock).
The grave errors that have been maintained in psychology for centuries are mostly due to a neglect of the comparative and genetic methods and the narrow employment of self-observation, or the introspective method; they are also partly due to the fact that metaphysicians generally make their own highly developed mind—a scientifically trained reason—the starting-point of their inquiry, and regard this as representative of the human mind in general, and thus build up their ideal scheme. The gulf between this thoughtful mind of civilized man and the thoughtless animal soul of the savage is enormous—greater than the gulf that separates the latter from the soul of the dog. Kant would have avoided many of the defects of his critical philosophy, and would not have formulated some of his powerful dogmas (such as the immortality of the soul, or the categorical imperative) if he had made a thorough and comparative study of the lower soul of the savage, and phylogenetically deduced the soul of civilized man therefrom.
The extreme importance of this comparison has only been fully appreciated of late years (by Lubbock, Romanes, etc.). Fritz Schultze (of Dresden) made the first valuable attempt in his interestingPsychology of the Savage(1900) to give us an "evolutionary psychological description of the savage in respect of intelligence, æsthetics, ethics, and religion." At the same time, he gives us "a history of the natural creation of the human imagination, will, and faith." The first book of this important work deals with thought, the second with will, and the third with the religious ideas of the savage, or "the story of the natural evolution of religion" (fetichism,animism, worship of the heavenly bodies). In an appendix to the second book the author deals with the difficult problems of evolutionary ethics, supporting himself by the authority of the great work of Alexander Sutherland,The Origin and Growth of the Moral Instinct(1898). Sutherland divides humanity, in regard to the various stages of civilization and mental development (not according to racial affinity), into four great classes: 1, Savages; 2, barbarians; 3, civilized races; 4, educated races. As this classification of Sutherland's not only enables us to take a good survey of the various forms of mental development, but is also very useful in connection with the question of the value of life at the different stages, I will briefly reproduce the chief points of his characterization of the four classes.
I.Savages.—Their food consists of wild natural products (the fruits and roots of plants, and wild animals of all kinds). Most of them are, therefore, fishers or hunters. They are ignorant of agriculture and the breeding of cattle. They live isolated lives in families or scattered in small groups, and have no fixed home. The lowest and oldest savages come very close to the anthropoid apes from which they have descended, in bodily structure and habits. We may distinguish three orders in this class—the lower, middle, and higher savages.
A.Lower savages, approaching nearest to the ape, pygmies of small stature, four to four and a half feet high (rarely four and three-quarters); the women sometimes only three to three and a half feet. They are woolly haired and flat-nosed, of a black or dark brown color, with pointed belly, thin and short legs. They have no homes, and live in forests and caverns, and partly on trees; wander about in small families of ten to forty persons; quite naked, or with just a trace of some primitive garment. Of the lower races now livingwe must put in this class the Veddahs of Ceylon, the Semangs of the Malay Peninsula, the Negritos of the Philippines, the Andaman Islanders, the Kimos of Madagascar, the Akkas of Guinea, and the Bushmen of South Africa. Other scattered remnants of these ancient negroid dwarfs, which approach closely to the anthropoid apes, still live in various parts of the primitive forests of the Sunda Islands (Borneo, Sumatra, Celebes).
The value of the life of these lower savages is like that of the anthropoid apes, or very little higher. All recent travellers who have carefully observed them in their native lands, and studied their bodily structure and psychic life, agree in this opinion. Compare the thorough treatment of the Veddahs of Ceylon in the work of the brothers Sarasin (of which I have given a summary in myTravels in Ceylon). Their only interests are food and reproduction, in the same simple form in which we find these among the anthropoid apes (cf.chapters xv. and xxiii. of myAnthropogeny). Our own ancestors were probably much the same ten thousand or more years ago. On the strength of fossil remains of Pleistocene men Julius Kollmann has shown it to be very probable that similar dwarf races (with an average height of four and a half feet) inhabited Europe at that time.
B.Middle savages, somewhat larger and less apelike than the preceding, averaging five to five and a half feet in height. Their homes are rock caverns and shelters from the wind and rain. Though they have shirts and other rudiments of clothing, both sexes generally go naked; they have primitive weapons of wood and stone and rudely fashioned boats, wander in troops of fifty to two hundred, and have no social organization; certain races, however, have laws. To this group belong the Australian negroes and Tasmanians,the Ainos of Japan, the Hottentots, Fuegians, Macas, and some of the forest races of Brazil. The value of their life is very little superior to that of the preceding order.
C.Higher savages, mostly of average human height (smaller in colder regions), having always simple dwellings (generally of skins or the bark of trees). They have always primitive clothing, and good weapons of stone, bronze, or copper. They wander in troops of one hundred to five hundred, led by prominent but not ruling princes, and exhibiting rudimentary differences of rank. The method of life is determined by hereditary customs. To this group belong many of the primitive inhabitants of India (Todas, Nagas, Curumbas, etc.), the Nicobar Islanders, the Samoyeds, and Kamtschadals; in Africa, the negroes of Damara; and most of the Indian tribes of North and South America. Their life is higher than that of the pithecoid lower and middle savages, but less than that of the barbarians.
II.Barbarians or Semi-savages.—The greater part of their food consists of natural products, which they secure with some foresight; hence they have developed agriculture and pasture to a greater or less extent. The division of labor is slight, each family supplying its own wants. As a rule, a stock of food is provided for the whole year. As a result of this, art begins to develop. They have generally fixed dwellings.
A.Lower Barbarians. Dwellings: Simple huts, generally grouped into villages and surrounded with plantations. Clothing worn regularly, but very simple: the men often naked in hot climates or with shirt. Pottery and cooking utensils, tools of stone, wood, or bone. Rudiments of commerce by exchange. Groups of one thousand to five thousand persons able to form larger communities; distinctions of rank and warfare. Princes rule according to traditional laws. Of this groupwe have in Asia many of the aboriginal inhabitants of India (Mundas, Khonds, Paharias, Bheels, etc.), the Dyaks of Borneo, the Battaks of Sumatra, Tunguses, Kirgises, etc.; in Africa the Kaffirs, Bechuanas, and Basutos; in Australasia the aborigines of New Guinea, New Caledonia, New Hebrides, New Zealand, etc.; and in America the Iroquois and Thlinkets, and the inhabitants of Nicaragua and Guatemala.
B.Middle barbarians. Dwellings good and durable, generally of wood, roofed with cane or straw, forming fine towns. Clothing general, though nudity is not considered immoral. Pottery, weaving, and metal-work pretty well developed. Commerce in regular markets, with the use of money. States ruled by kings in accordance with traditional laws, fixed distinctions of rank, communities up to one hundred thousand persons. To these belong in Asia the Calmucks; in Africa many negro races (Ashantis, Fantis, Fellahs, Shilluks, Mombuttus, Owampos, etc.); in Polynesia the inhabitants of the Fiji, Tonga, Samoa, and Markesas islands. In Europe the Lapps belonged to this class two hundred years ago, the ancient Germans two thousand years ago, the Romans before Numa, and the Greeks of the Homeric period.
C.Higher barbarians. Dwellings, usually solid stone buildings. Clothing obligatory, weaving habitual occupation of the women, metal-work far advanced, tools generally of iron. Restricted commerce, with minted money, no rudder-ships. Crude judicature in fixed courts; rudimentary writing. Masses of people, with progressive division of labor and hereditary distinctions of rank, sometimes reaching half a million souls, under an autonomous ruler. To this class belong in Asia most of the Malays (in the large Sunda Islands and the peninsula of Malacca), and the nomadic races of Tartars, Arabs, etc.; in Polynesia the islanders of Tahiti andHawaii; in Africa the Somalis and Abyssinians, and the inhabitants of Zanzibar and Madagascar. Of the historic peoples of antiquity we have the Greeks of the time of Solon, the Romans at the beginning of the republic, the Jews under the Judges, the Anglo-Saxons of the Heptarchy, and the Mexicans and Peruvians at the time of the Spanish invasion.
III.Civilized Races.—Food and complex vital needs are easily satisfied on account of the advanced division of labor and improvement of instruments. Art and science are consequently developed more and more. The increasing specialization brings about a great elaboration of individual functions, and at the same time a great strengthening of the whole body politic, as there is complete mutual dependence. The citizens see that they must submit to the laws of the state.
A.Lower civilized races. Towns with stone walls; vast architectural works in stone; use of the plough in agriculture. War is intrusted to a particular class. Writing firmly established, primitive law-books, fixed courts. Literature begins to develop. To this group belong in Asia the inhabitants of Thibet, Bhutan, Nepaul, Laos, Annam, Korea, Manchuria, and the settled Arabs and Turcomans; in Africa the Algerians, Tunisians, Moors, Kabyles, Tuaregs, etc. Of historical races we have the ancient Egyptians, Phœnicians, Assyrians, Babylonians, Carthaginians, the Greeks after Marathon, the Romans of the time of Hannibal, and the English under the Norman kings.
B.Middle civilized races. Beautiful temples and palaces, built of stone and brick. Windows come into use, and sailing-ships. Commerce expands. Writing and written books are general; the literary instruction of the young is attended to. Militarism is further developed; so are legislation and advocacy. Of these we have in Asia the Persians, Afghans, Birmans, andSiamese; in Europe the Finns and Magyars of the eighteenth century. Of historical peoples we must count among them the Greeks of the age of Pericles, the Romans of the later republic, the Jews under the Macedonian rule, France under the first Capets, and England under the Plantagenets.
C.Higher civilized races. Stone houses general; streets paved; chimneys, canals, water and wind mills. Beginnings of scientific navigation and warfare. Writing general, written books widely distributed, literature esteemed. The highly centralized state embraces communities of ten millions or more. Fixed and written codes of law are officially promulgated and applied by courts to particular cases. Numbers of government officials have settled rank. To this group belong in Asia the Chinese, Japanese, and Hindoos; also the Turks and the various republics of South America, etc. In history we have the Romans of the empire, and the Italians, French, English, and Germans of the fifteenth century.
IV.Cultivated Races.—Food and other needs are artificially supplied with the greatest ease and in abundance, human labor being replaced by natural forces. The social organization grows and facilitates the play of all the social forces, and man obtains a great freedom to cultivate his mental and æsthetic qualities. Printing is in general use, the education of the young one of the first duties. War becomes less important; rank and fame depend less on military bravery than on mental superiority. Legislation is influenced by representatives of the people. Art and science are increasingly promoted by state aid.
Alexander Sutherland distinguishes three stages of development—the lower, middle, and higher—in the fourth as well as in the preceding classes. To the first stage he assigns "the leading nations of Europe andtheir offshoots, such as the United States of North America." For the second stage—middle cultured races—he gives a programme that may be carried out in three or four hundred years' time, with this definition: "All men are well fed and housed; war is universally condemned, but breaks out now and again. Small armies and fleets of all the nations co-operate as a sort of international police; commercial and industrial life are directed according to the moral precepts of sympathy; culture is general; crime and punishment rare." Of the third and highest stage Sutherland merely says, "Too bold a subject for prophecy, that may not come for one thousand to two thousand years yet." This division seems to me too vague and unsatisfactory, in the sense that it does not properly emphasize the civilization of the nineteenth century in contrast with all preceding stages. It would be better to distinguishprovisionallythe following stages in modern civilization: first, sixteenth to eighteenth century; second, nineteenth century; and third, twentieth century and the future.
A.Lower cultured races (Europe, sixteenth to eighteenth century). At the commencement of this period, the first half of the sixteenth century, we notice the preparatory movements to the full growth of mental life which was to achieve such great results in the following periods: 1. The cosmic system of Copernicus (1543) maintained by Galileo (1592). 2. The discovery of America by Columbus (1492) and of the East Indies by Vasco da Gama (1498), the first circumnavigation of the earth by Magellan (1520) and the evidence it afforded of the rotundity of the earth. 3. The liberation of the mind of Europe from the papal yoke by Martin Luther (1517) and the repulse of the prevailing superstition by the spread of the Reformation. 4. The new impulse to scientific investigation independently ofscholasticism and the Church and of the philosophy of Aristotle; the founding of empirical science by Francis Bacon (1620). 5. The spread of scientific knowledge by the press (Gutenberg, 1450) and wood-engraving. The way was prepared for modern civilization by these and other advances in the sixteenth century, and it quickly arose above the barbaric level of the Middle Ages. However, it was confined at first within narrow limits, as the reactionary civilization of the Middle Ages was still powerful in political and social life, and the struggle against superstition and unreason made slow progress. The French Revolution (1792) at last gave a great impetus in practical directions.
B.Middle cultured races. This name may be given to the leading nations of Europe and North America in the nineteenth century. We may illustrate in the following achievements the great advance which this "century of science" made as compared with all preceding ages: 1. Deepening, experimental grounding, and general spread of a knowledge of nature; independent establishment of many new branches of science; founding of the cell-theory (1838), the law of energy (1845), and the theory of evolution (1859). 2. Practical and comprehensive application of this theoretical science to all branches of art and industry. Especially 3. The overcoming of time and space by the extraordinary speed of transit (steamboats, railways, telegraphs, electrotechnics). 4. Construction of the monistic and realistic philosophy, in opposition to the prevailing dualistic and mystical views. 5. Increasing influence of rational scientific instruction and abandonment of the religious fiction of the Churches. 6. Increasing self-consciousness of the nations on account of having a share in government and legislation; extinction of the belief in the divine right of rulers. New distinction of classes. However, these great advances, to which we children ofthe nineteenth century may point with pride, are far from being universal; they are struggling daily with reactionary views and powers in Church and state, with militarism, and with ancient and venerable immorality of every kind.
C.The higher culture which we are just beginning to glimpse will set itself the task of creating as happy and contented a life as possible for all men. A perfect ethic, free from all religious dogma and based on a clear knowledge of natural law, will be found in the golden rule, "Love thy neighbor as thyself." Reason tells us that a perfect state must provide the greatest possible happiness for every individual that belongs to it. The adjustment of a rational balance between egoism and altruism is the aim of our monistic ethics. Many barbaric customs that are still regarded as necessary—war, duelling, ecclesiastical power, etc.—will be abolished. Legal decisions will suffice to settle the quarrels of nations, as they now do of individuals. The chief interest of the state will be, not the formation of as strong a military force as possible, but the best possible instruction of its young, with special attention to art and science. The improvement of technical methods, owing to new discoveries in physics and chemistry, will bring greater satisfaction of our needs of life. The artificial production of albumin will provide plenty of food for all. A rational reform of the marriage relations will increase the happiness of family life.
The darker sides of modern life, of which we are all more or less sensitive, have been laid bare by Max Nordau in hisConventional Lies of Civilization. They will be greatly altered if reason is permitted to have its way in practical life, and the present evil customs, based on antiquated dogmas, are suppressed. But, in spite of all these shades, the luminous features of modern civilization are so great that we look to the future with hopeand confidence. We need only glance back half a century, and compare life to-day with what it was then, in order to realize the progress made. If we regard the modern state as an elaborate organism (a "social individual of the first order"), and compare its citizens to the cells of a higher tissue-animal, the difference between the state of to-day and the crudest family groups of savages is not less than that between a higher metazoon (such as a vertebrate) and a cœnobium of protozoa. The progressive division of labor, on the one hand, and the centralization of society, on the other, prepare the social body for higher functions than in isolation, and proportionately increase the worth of its life. To see this more clearly, let us compare the personal and the social value of life in the five chief fields of vital activity—nutrition, reproduction, movement, sensation, and mental life.
The first need of the individual organism, self-maintenance, is met in a much more perfect manner in the modern state than it was formerly. The savage is satisfied with the raw products of nature—with hunting, fishing, and the gathering of roots and fruits. Agriculture and pasturage come later. Many stages of barbarism and lower civilization must be passed before the conditions of feeding, housing, and clothing provide a secure and comfortable existence for man, and permit the addition of æsthetic and intellectual interests to the indispensable search for food.
The feeding and condition of the social body as a whole have been improved by modern civilization, just as in the case of the individual. The progress of chemistry and agriculture has enabled us to produce food in larger quantities. The ease and rapidity of transfer allow it to be distributed over the whole earth. Scientific medicine and hygiene have discovered many means of diminishing the dangers of disease and preventing itsoccurrence. By means of public baths, gymnasiums, popular restaurants, public gardens, etc., greater care is taken of the health of the community. The arrangement of modern houses and their heating and lighting have been immensely improved. Modern social politics strives more and more to extend these benefits of civilization to the lower classes. Philanthropic societies are busy supplying the material and spiritual wants of various classes of sufferers. It is true there is still a broad margin for the improvement of the national well-being. But, on the whole, it cannot be denied that the provision of food in the modern state is an immense advance upon that of the Middle Ages and of the barbaric period.
The great value of modern civilization and its vast progress beyond the condition of the savage is seen in no branch of physiology so conspicuously as in the wonderful process of reproduction and the maintenance of the species. In most savages and barbarians the satisfaction of their powerful sexual impulse is at the same low stage as in the ape and other mammals. The woman is merely an object of lust to the man, or even a slave without rights, bought and exchanged like all other property. Improvement is slow and gradual in the value of this property, until it reaches a high guarantee of permanency in the formal marriage. The family life proves a source of higher and finer enjoyment for both parties. The position of woman advances with civilization; her rights obtain further recognition, and in addition to sensual love the psychic relation of man and wife begins to develop. The common concern for the proper care and education of the children, which we find to an extent even in the case of many animals, leads to the further development of family life and the founding of the school. With the advent of a higher stage of civilization begins the refinement of sexual love, which finds its highest satisfaction, not in the momentarygratification of the sex-impulse, but in the spiritual relation of the sexes and their constant and intimate intercourse. The beautiful then unites with the good and the true to form a harmonious trinity. Hence love has been for thousands of years the chief source of the æsthetic uplifting of man in every respect; the arts—poetry, music, painting, and sculpture—have drawn inexhaustively from this source. However, for the individual civilized human being this higher love is of value, not only because it satisfies the natural and irresistible sex-impulse in its noblest form, but also because the mutual influence of the sexes, their complementary qualities and their common enjoyment of the highest ideal good, has a great effect upon individual character. A good and happy marriage—which is not very common to-day—ought to be regarded, both psychologically and physiologically, as one of the most important ends of life by every individual of the higher nations.
As a pure marriage is the best form of family life and the most solid foundation of the state, its high social value is at once evident. The attraction and mutual devotion of the sexes fulfils in the highest degree the ethical golden rule—the balance of egoism and altruism. As Fritz Schultze very truly says in hisComparative Psychology
We must not seek the causes of this altruism in the transcendental region of the supernatural, or in any metaphysical abstraction, but must go back to the very real and natural qualities of the organic being—and then there can be no question that the organic sex-impulse, at once physical and psychical is the first and enduring source of all love, however spiritual, and of all real ethical and sympathetic feelings and the morality founded thereon. There are two primitive instincts in all organisms: that of self-maintenance and that of the maintenance of the species. The one is the strong impulse of egoism, the other the spring of altruism: from the one come all unfriendly and from the other all friendly feelings. Every being seeksfirst to nourish and protect itself in virtue of its instinct of self-maintenance. But soon the magic of the instinct for the maintenance of the species works in it; it feels the sex-impulse, and thinks it is only satisfying its egoistic lust in yielding to it. In this it is wrong; it is not really serving itself, but the whole, the species, the genus. The ardor of love burns in it; and however sensual this love is at first, the new feeling is undeniably a feeling of belonging to another and of mutual consideration, looking not only to itself, but to another; not only to its own good, but to that of another, and finding its own good only in that of the other. And though this feeling at first only unites the two parents, it enlarges when children enter into life, and is extended to them in the form of parental love. Thus, out of the sex-impulse of the maintenance of the species, with its strong physical and psychic roots, is developed the love of spouses, of parents, of children, and of neighbor. Disinterested egoism goes even to the extent of sacrificing its own life for its young; in this organic and natural family love, and in the sense of the family that comes of it, we find the roots of all sympathetic and really ethical altruistic feelings; from this it widens out to larger spheres. Hence, the family is rightly held to be the chief source of all real moral feeling and life, not only in the human, but also in the animal world.
The further ennoblement of family life in the advance of civilization will give fresh proofs of the truth of this appreciation.
We now turn to consider the advantages that modern civilization offers in the way of movement in contrast to the simple methods of locomotion of the savage. We may point out first that the earliest men, like their ancestors, the anthropoid apes, lived in trees, and only gradually began to run on the ground. Some of the higher savages began to use the horse for riding and to tame it. Many inhabitants of the coast or islands began at an early period to make boats. Later the barbaric tribes invented the wagon, and much later again streets were paved and vehicles improved by civilized races. But the nineteenth century brought the invaluable means of rapid and convenient travelling by meansof steamboats and railways. The whole problem of transit was revolutionized, and in the last few decades further vast changes have been made owing to the advance of electricity. Modern ideas of time and space are quite different from those of our parents sixty years ago, or our grandparents ninety years ago. In our expresses we cover in an hour a stretch of country that the mail-coach took five times and the foot-passenger ten times as long to cover. As the experiments with the Berlin electric railway have lately shown, we can now travel two hundred kilometres in an hour. The journey from Europe to India now takes three weeks, whereas the earlier sailing-vessel took as many months. The immense saving of time that we make is equivalent to a lengthening of our own life. This applies also to the more rapid transit provided by balloons, automobiles, bicycles, etc. It is easy to estimate the value of these improvements; but it is only fully appreciated by those who have lived long in an uncivilized country without roads or among savages whose legs are their only means of locomotion.