HEREDITY AND SELECTIONIN SOCIOLOGY

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“To it the interested reader will turn with expectation, and his expectation is likely to be more than realised. For Dr. Boyce Gibson is himself a scholar, as well as an enthusiastic lover of this great scholar.”—Expository Times.

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FOOTNOTES:1Windelband (Geschichte und Naturwissenschaft, 3 Auflage, 1904) gives the name “nomothetic” to the whole of our “science” and calls the method of history “idiographic.” We thought it better to establish three fundamental types of all possible branches of knowledge.2See J. Arth. Thomson,The Science of Life, London, 1899.3E. B. Wilson,The Cell in Development and Inheritance, New York, Macmillan, 1896.4Amer. Journ. Physiol.vols. iii. and iv. 1900.5According to Delage (Arch. Zool. exp., 3 sér. 10, 1902), it is indifferent for the realisation of artificial parthenogenesis, whether but one, or both, or neither of the “polar bodies” has been formed. But the egg must be in the first stages of maturation to the extent that the “nuclear membrane” must be already dissolved.6The older theories, attributing to fertilisation (or to “conjugation,”i.e.its equivalent in Protozoa), some sort of “renovation” or “rejuvenescence” of the race, have been almost completely given up. (See Calkins,Arch. für Entwickelungsmechanik, xv. 1902). R. Hertwig recently has advocated the view, that abnormal relations between the amounts of nuclear and of protoplasmatic material are rectified in some way by those processes. Teleologically, sexual reproduction has been considered as a means of variability (Weismann), but also as a means of preserving the type!7The phrase “ceteris paribus” has to be added of course, as the duration of each single elementary morphogenetic process is liable to vary with the temperature and many other conditions of the medium.8We shall not avoid in these lectures the word “explain”—so much out of fashion nowadays. To “explain” means to subsume under known concepts, or rules, or laws, or principles, whether the laws or concepts themselves be “explained” or not. Explaining, therefore, is always relative: what is elemental, of course, is only to be described, or rather to be stated.9Das Keimplasma, Jena, 1892.10Die Bedeutung der Kernteilungsfiguren, Leipzig, 1883.11Unsere Körperform, Leipzig, 1875.12Die Entwickelungsgeschichte der Unke, Leipzig, 1875.13Gesammelte Abhandlungen, Leipzig, 1895. Most important theoretical papers:—Zeitschr. Biolog.21, 1885;Die Entwickelungsmechanik der Organismen, Wien, 1890;Vorträge und Aufsätze über Entwickelungsmechanik, Heft i., Leipzig, 1905.14Virchow’s Archiv.114, 1888.15Zeitschr. wiss. Zool.53, 1891.16Zeitschr. wiss. Zool.55, 1892.17In the pressure experiments I had altered the relative position of the nucleiin origine. In later years I succeeded in disturbing the arrangement of the fully formed cells of the eight-cell stage, and in getting normal larvæ in spite of that in many cases. But as this series of experiments is not free from certain complications—which in part will be understood later on (see page73)—it must suffice here to have mentioned them. (For further information see my paper inArchiv. f. Entwickelungsmechanik, xiv., 1902, page 500.)18Mitteil. Neapel. 11, 1893.19But the elementary magnets would have to be bilateral!20Arch. Entw. Mech.2, 1895.21Anat. Anz.10, 1895.22Arch. Entw. Mech.3, 1896.23It deserves notice in this connection, that in some cases the protoplasm of parts of a germ has been found to be more regulable in the earliest stages, when it is very fluid, than later, when it is more stiff.24Compare myAnalytische Theorie der organischen Entwickelung, Leipzig, 1894, and my reviews inErgebnisse der Anatomie und Entwickelungsgeschichte, vols. viii. xi. xiv., 1899–1905. A shorter review is given inErgebnisse der Physiologie, vol. v., 1906. The full literature will be found in these reviews.25If the plane of section passes near the equator of the germ, two whole larvae may be formed also, but in the majority of cases the “animal” half does not go beyond the blastula. The specific features of the organisation of the protoplasm come into account here. See also page65, note17.26A change of the position of the cell is of course effected by each variation of the direction of the cut, which is purely a matter of chance.27The reader will remember (see page65, note17), that even the germ of Echinus is not quite equipotential along its main axis, but it is equipotential in the strictest sense around this axis. The germs of certain medusae seem to be equipotential in every respect, even in their cleavage stages.28Journ. Exp. Zool.1, 1904.29Great caution must be taken in attributing any specific morphogenetic part to differently coloured or constructed materials, which may be observed in the egg-protoplasm in certain cases. They may play such a part, but in other cases they certainly do not (see Lyon,Arch. Entw. Mech.23, 1907). The final decision always depends on experiment.30It seems that these physical conditions also—besides the real specifications in the organisation of the egg—may be different before and after maturation or (in other cases) fertilisation. (See Driesch,Archiv f. Entwickelungsmechanik, 7, p. 98; and Brachet,ibid.22, p. 325.)31Studien über Protoplasmamechanik, Leipzig, 1886.32Unters. üb. mikroskopische Schäume und das Protoplasma, Leipzig, 1892.33Jena. Zeitschr.26, 1892.34According to Zur Strassen’s results the early embryology ofAscarisproceeds almost exclusively by cellular surface-changes: the most typical morphogenetic processes are carried out by the aid of this “means.” As a whole, the embryology ofAscarisstands quite apart and presents a great number of unsolved problems; unfortunately, the germ of this form has not been accessible to experiment hitherto.35Rhumbler has recently published a general survey of all attempts to “explain” life, and morphogenesis in particular, in a physico-chemical way (“Aus dem Lückengebiet zwischen organismischer und anorganismischer Natur,”Ergeb. Anat. u. Entw.-gesch.15, 1906). Thisvery pessimisticsurvey is the more valuable as it is written by a convinced “mechanist.”36Compare the analytical discussions of Klebs, to whom we owe a great series of important discoveries in the field of morphogenetic “means” in botany. (Willkürliche Entwickelungsänderungen bei Pflanzen, Jena, 1903; see alsoBiol. Centralblatt, vol. xxiv., 1904, and my reply to Klebs,ibid.23, 1903.)37Arch. Entw. Mech.17, 1904.38Zeitschr. wiss. Zool.55, 1902; andMitt. Neapel.11, 1903.39In certain cases part of the specific feature of the process in question may also depend on the “cause” which is localising it,e.g.in the galls of plants.40Herbst, “Ueber die Bedeutung die Reizphysiologie für die kausale Auffassung von Vorgängen in der tierischen Ontogenese” (Biol. Centralblatt, vols. xiv., 1894, and xv., 1895);Formative Reize in der tierischen Ontogenese, Leipzig, 1901. These important papers must be studied by every one who wishes to become familiar with the subject. The present state of science is reviewed in my articles in theErgebnisse der Anatomie und Entwickelungsgeschichte, vols. xi. and xiv., 1902 and 1905.41Compare the important papers by J. Loeb,Untersuchungen zur physiologischen Morphologie der Tiere, Würzburg, 1891–2.42I use the word “primordia” for the German “Anlage”; it is better than the word “rudiment,” as the latter may also serve to signify the very last stage of a certain formation that is disappearing (phylogenetically).43A full analysis of the subject would not only have to deal with formative stimuli as inaugurating morphogenetic processes, but also with those stimuli which terminate or stop the single acts of morphogenesis. But little is actually known about this topic, and therefore the reader must refer to my other publications. I will only say here, that the end of each single morphogenetic act may either be determined at the very beginning or occur as an actual stopping of a process which otherwise would go on for ever and ever; in the first case some terminating factors are included in the very nature of the morphogenetic act itself.44A full account of the present state of the subject will be found in Morgan’sExperimental Zoology, New York, 1907.45But there certainly exist many formative relations between the real sexual organs and the so-called secondary sexual characters. Herbst has given a full analytical discussion of all that is known on this subject; but the facts are much more complicated than is generally supposed, and do not lend themselves therefore to short description. See also Foges,Pflüger’s Arch.93, 1902.46It seems that in some cases (Dinophilus, certain Arthropods) the sexual products are invariably determined as “arrenogennetic” or as “thelygennetic” (Wilson,Journ. Exp. Zool.ii. and iii. 1905–6), whilst in others (Amphibia) the state of maturation or “super”-maturation determines the sex of the future organism (R. Hertwig,Verh. D. Zool. Ges.1905–7).47Driesch,Die organischen Regulationen, Leipzig, 1901; Morgan,Regeneration, New York, 1901.48But real compensatory differentiation occurs in the cases of so-called “hypertypy” as first discovered by Przibram and afterwards studied by Zeleny: here the two organs of a pair show a different degree of differentiation. Whenever the more specialised organ is removed the less developed one assumes its form. Similar cases, which might simply be called “compensatory heterotypy,” are known in plants, though only relating to the actual fate of undifferentiated “Anlagen” in these organisms. A leaf may be formed out of the Anlage of a scale, if all the leaves are cut off, and so on.49For a fuller analysis compare my opening address delivered before the section of “Experimental Zoology” at the Seventh Zoological Congress, Boston, 1907: “The Stimuli of Restitutions” (see Proceedings of that Congress).50The problem of the stimulus of a secondary restitution as a whole must not be confused with the very different question, what the single “formative stimuli” concerned in the performance of a certain restitutive act may be. With regard to restitution as awholethese single “formative stimuli” might properly be said to belong to its “internal means”—in the widest sense of the word.51T. H. Morgan is very right in stating that, in regeneration, the “obstacle” itself is newly formed by the mere process of healing, previous to all restitution, and that true restitution happens all the same.52I merely mention here the still “simpler” one—applicable of course to regeneration proper exclusively—that for the simple reason of being “wounded,”i.e.being a surface open to the medium, the “wound” brings forth all that is necessary to complete the organism.53That compensatory hypertrophy cannot be due to “functional adaptation”—to be analysed later on—was proved by an experiment of Ribbert’s. Compensation may occur before the function has made its appearance, as was shown to be the case in the testicles and mammae of rabbits. (Arch. Entw. Mech.1, 1894, p. 69.)54At any given time only the absolute size of the regenerated part is greater in animals which are well fed; the degree of differentiation is the same in all. Zeleny has found that, if all five arms of a starfish are removed, each one of them will regenerate more material in a given time than it would have done if it alone had been removed. But these differences also only relate to absolute size and not to the degree of differentiation. They possibly may be due in fact to conditions of nourishment, but even here other explanations seems possible (Zeleny,Journ. exp. Zool.2, 1905).55For a good discussion of “super-regeneration” in the roots of plants see Němec,Studien über die Regeneration, Berlin, 1905. Goebel and Winkler have succeeded in provoking the “restitution” of parts which were not removed at all by simply stopping their functions (leaves of certain plants were covered with plaster, etc.). (Biol. Centralbl.22, 1902, p. 385;Ber. Bot. Ges.20, 1902, p. 81.) A fine experiment is due to Miehe. The algaCladophorawas subjected to “plasmolysis,” each cell then formed a new membrane of its own around the smaller volume of its protoplasm; after that the plants were brought back to a medium of normal osmotic pressure, and then each single cell grew up into a little plant (all of them being of the same polarity!). Two questions seem to be answered by this fact: loss of communication is of fundamental importance to restitution, and the removal of mechanical obstacles plays no part in it, for the mechanical resistances were the same at the end of the experiment as they had been at the beginning. (Ber. Bot. Ges.23, 1905, p. 257.) For fuller analysis of all the problems of this chapter see my Organische Regulationen, my reviews in theErgebnisse der Anatomie und Entwickelungsgeschichte, vols. viii. xi. xiv., and my Boston address mentioned above. Compare also Fitting,Ergebn. d. Physiol.vols. iv. and v.56The so-called “inner secretion” in physiology proper would offer a certain analogy to the facts assumed by such an hypothesis. Compare the excellent summary given by E. Starling at the seventy-eighth meeting of the German “Naturforscherversammlung,” Stuttgart, 1906.57The name of singular-equipotential systems might also be applied to elementary organs, the single potencies of which are awaked to organogenesis by specific formative stimuli from without; but that is not the case in the systems studied in this chapter.58The distance of the other boundary line fromaorbwould be given by the value ofs.59A far more thorough analysis of this differentiation has been attempted in my paper, “Die Localisation morphogenetischer Vorgänge. Ein Beweis vitalistischen Geschehens,” Leipzig, 1899.60This statement isnot strictlycorrect forTubularia. I found (Archiv f. Entwickelungsmechanik, ix. 1899), that a reduction of the length of the stem is always followed by a reduction of the size of the hydranth-primordium, but there is no real proportionality between them. It is only for theoretical simplification that a strict proportionality is assumed here, both in the text and the diagram. But there is an almost strict proportionality in all cases of “closed forms.”61One might object here that in a piece of aTubulariastem, for instance, the tissues are in direct contact with the sea-water at the two points of the wounds only, and that at these very points a stimulus might be set up—say by a process of diffusion—which gradually decreases in intensity on its way inward. And a similar argument might apply to the small but whole blastula of Echinus, and to all other cases. But, in the first place, stimuli which only differ in intensity could hardly call forth the typical and typically localised single features realised in differentiation. On the other hand—and this will overthrow such an hypothesis completely—the dependence of the single localised effects in every case on theabsolute sizeof the fragment or piece chosen for restoration renders quite impossible the assumption that all the singularities in the differentiation of the harmonious systems might be called forth by single stimuli originating in two fixed places in anindependentway. These would never result in any “harmonious,” any proportionate structure, but a structure of the “normal” proportionalityand sizeat its two ends and non-existent in the middle!62See my article inBiolog. Centralblatt, 27, 1907, p. 69. The question is rendered still more complicated by the fact that in the case of the regeneration, say, of a leg it is not the original “morphogenetic compound” which is again required for disintegration, after it has become disintegrated once already, but only a specific part of it: just that part of it which is necessary for producing the leg! On the other hand, it would be impossible to understand, on the basis of physical chemistry, how the isolated branchial apparatus ofClavellinacould be transformed, by chemical processes exclusively, into a system of which only a certainpartconsists of that substance of which the starting-point had been composed in itscompleteness.63Besides the specified poles determined by the polar-bilateral structure of the protoplasm.64The pressure experiments and the dislocation experiments come into account here; for the sake of simplicity they have not been alluded to in the main line of our argument.65My “first proof of vitalism” was first developed in the paper, “Die Localisation morphogenetischer Vorgänge,” Leipzig, 1899. (See additional remarks inOrganische Regulationem, Leipzig, 1901, and inArchiv für Entwickelungsmechanik, 14, 1902.) I cannot admit that any really serious objection has been brought forward against it. (See my articles inBiologisches Centralblatt, 22, 23, 27, and inErgebnisse d. Anat. u. Entwickelungsgesch. 11, 14.) An historical sketch of vitalism will be found in my book,Der Vitalismus als Geschichte und als Lehre, Leipzig, 1905.66We are dealing here with morphogenesis and so-called vegetative physiology only; to certain psychologists, who have refuted the theory of psycho-physical parallelism, I must grant that they also have proved vitalism. (See Volume II.)67The eight larvae would be incomplete in some respect, but not with regard to symmetry. They would be “whole” ones, only showing certain defects in their organisation. See page65note17, and page73.68Reciprocal harmony may be reduced in some cases to the given proportions of one original harmonious system, from which the single constituents of the complicated system, showing reciprocal harmony, are derived. Then we have only an instance of “harmony of constellation” (see p.109). But reciprocal harmony seems to become a problem itself, if it occurs in restitutions starting from quite a typical point, selected by the experimenter. It will be a problem of future research to give an exact formula of what happens here. Reciprocal harmony also occurs in regeneration proper. It is known that the formation of the regenerative bud and the differentiation of this bud follow each other. As the bud is composed of different elementary systems, it follows that these different systems, of which every single one is harmonious, also have to work in reciprocity to each other, in order that one whole proportionate formation may result.69Biol. Centralblatt.23, 1903.70Certain phenomena of the physiology of growth ofGeranium Robertianum, recently discussed by Francé from a vitalistic point of view (Zeitschr. Entw. lehre. 1, 1907, Heft iv.), might also belong here. I cannot see an independent proof of vitalism in these facts if taken by themselves; a pre-existing “machine” cannot be absolutely excluded here.71Driesch,Arch. Entw. Mech.5, 1897.72Driesch,Arch. Entw. Mech.14, 1902.73The root may be restored by regeneration proper, or by the production of adventitious roots, or by one of the side-roots changing its geotropism from horizontal to positive, according to the smaller or greater distance of the wound from the tip.74“Retro”-differentiation, of course, is not “Re”-differentiation (“Umdifferenzierung,” see p.111), though it may help it to occur.75Of course such a real decay of parts may happen in other cases.76Certain cases of retro-differentiation occurring under conditions of strict fasting will be described in a later chapter.77Klebs has suppressed the reproductive phase of organisation altogether, in fungi as well as in flowering plants, or has made it occur abnormally early, merely by changing the “external conditions” and by altering the “internal” ones correspondingly. There is hardly anything like an adaptation in these cases, which, by the way, offer certain difficulties to analysis, as the boundaries between “cause” and “means” are not very sharp here.78Compare Herbst,Biol. Centralbl.15, 1895; and Detto,Die Theorie der direkten Anpassung, Jena, 1904. A full account of the literature will be found in these papers.79Vöchting (Jahrb. wiss. Bot.34, 1899) forced the bulbs of plants to become parts of the stem, and parts of the stem to form bulbs; in both cases the most characteristic changes in histology could be observed, being in part adaptations, but in part restitutions of the proper type. (See also myOrganische Regulationen, 1901, p. 84.) A true and simple instance of a “secondary adaptation” seems to be furnished in a case described by Boirivant. InRobiniaall the leaflets of a leaf-stalk were cut off: the leaf-stalk itself then changed its structure in order to assist assimilation, and also formed real stomata.80Arch. Entw. Mech.17, 1904.81Roux,Gesammelte Abhandlungen, vol. i. 1895; in particular,Der Kampf der Teile im Organismus, Leipzig, 1881.82Arch. Entw. Mech.21, 1906. By a very detailed comparative study Babák was able to prove that it is the plant proteids to which the effect of vegetable food is chiefly due; thus we have an adaptation to digestibility. Mechanical circumstances are only of secondary importance. (See also Yung.)83Atrophy of muscles by inactivity is not to be confused with atrophy by cutting the motor nerve; the latter is very much more complete.84Loeb has advocated the view that the “adaptive” growth of working muscles is simply due to the presence of a greater number of molecules in their protoplasm, muscular activity being generated by a process of chemical decomposition.85What has been reallyprovedto exist by the very careful studies carried out by Child, is only certain cases of functional adaptation to mechanical conditions of the strictest kind, and relating to the general mobility only, but nothing more; such adaptations can be said to accompany restitution. See, for instance,Journ. exp. Zool.3, 1906, where Child has given a summary of his theory.86Even in Vöchting’s experiments (see page174, note79), in which adaptations are mixed with true restitutions in the closest possible manner, a few phenomena of the latter type could most clearly be separated. The stimulus which called them forth must have been one of the hypothetic sort alluded to in a former chapter (see page113). The best instances of true restitutions were offered in those cases, where, after the removal of all the bulbs, typical starch-storing cells were formed without the presence of any starch.87Beiträge zur Lehre von den Functionen der Nervencentren des Frosches, Berlin, 1869.88The “secondary adaptations” observed by Vöchting are too complicated and too much mingled with restitutions to allow any definite analysis of the fact of the “secondary adaptation” as such.89General literature: Fröhlich,Das natürliche Zweckmüssigkeitsprincip in seiner Bedeutung für Krankheit und Heilung, 1894. Driesch,Die organischen Regulationen, 1901. A. Tschermak, “Das Anpassungsproblem in der Physiologie der Gegenwart,” in a collection of papers in honour of J. P. Pawlow, St. Petersburg, 1904. Bieganski, “Ueber die Zweckmässigkeit in den pathologischen Erscheinungen,”Annal. d. Naturphil.5, 1906. Among the general text-books of physiology those by Pfeffer (Pflanzenphysiologie, 1897–1904) and von Bunge (Lehrbuch d. Phys. d. Menschen, 1901) are the fullest on the subject of “regulations.” See also different papers on general pathology by Ribbert.90According to investigations of the last two years, the physics of colloids seems to play as important a part in physiology as osmosis does; we here meet “means” of functioning just as we have already had “means” of organogenesis.91I only mention here that certain modern psychologists have assigned the true law of Weber to the sphere of judgment and not of sensation. If applied to objective reactions only, in their dependence on objective stimuli, it, of course, becomes less ambiguous, and may, in a certain sense, be said to measure “acclimatisation” with regard to the stimulus in question. The mathematical analogy of the law of Weber to the most fundamental law of chemical dynamics seems very important.As to “acclimatisation” in the more usual meaning of the word, with regard to a change of the general faculty of resisting certain agents of the medium, “immunity” proper is to form a special paragraph of what follows, and to “acclimatisation” towards different degrees of salinity (in algae or fishes) some special remarks will also be devoted on a proper occasion. There remains only “acclimatisation” to different temperatures; but on this topic not much more than the fact is known (see Davenport,Arch. f. Entw. Mech.2, p. 227). “Acclimatisation” does not allow of a sharp general definition; it may be the result of verydifferentkinds of adaptations in our sense of the word.92I should think that the problem of the re-establishment of irritability, in principle at least, arises even when there is not a trace of so-called “fatigue” or of a “refractory period.” The process of restoring may be so rapid as not to be noticeable, nevertheless some sort of restoring is to be postulated. We may say the “irritability” of an elastic ball is re-established by its elasticity. A certain analogy to this case may perhaps be found in the muscle. But the irritability of nerves with respect to nervous conduction, and of glands with respect to secretion, or of the articulations ofMimosamay be well understood, hypothetically at least, if we assume that the ordinary course of metabolic events is apt in itself to lead to a certain state or condition of the organs in question upon which their irritability is based. Certain general conditions of functioning, as for instance the presence of oxygen for the contraction of the muscle, would better be looked upon as necessary “means” of functioning than as being part of irritability as such. “Fatigue,” of course, may also be due to the absence of such “means” or to abnormal conditions originated by functioning itself.93Rubner,Die Gesetze des Energieverbrauches bei der Ernährung, Leipzig u. Wein, 1902.94The phenomenon of fever we leave out of account here; it is regarded by some as regulation, by others as a disturbance of heat regulation. Of course, if the first view should ever prove to be the right one, fever might be classified among the real regulations of the secondary type.95Jahrb. wiss. Bot.36, 1901.96Carbohydrates cannot be ionised, and therefore there is no doubt that in von Mayenburg’s experiments the organism itself is actively at work. As to compounds liable to ionisation, it has been noticed by Maillard that a certain regulatory character is contained simply in the physical fact that the degree of ionisation changes with concentration: decrease of concentration for instance would be followed by an increase of ionisation, and so the osmotic pressure may be preserved (C. rend. Soc. Biol.53, 1901, p. 880).97In the different experiments of Nathansohn (Jahrb. wiss. Bot.38, 1902, and 39, 1903) the salinity of the medium was changed in such a way that there was in each case either an abnormal increase or an abnormal decrease in the concentration of one single ion necessary for metabolism. The cell was found to stand these abnormal changes in such a way that in the case of the increase of the concentration of the medium it did not allow more than a certain amount of the ion in question to come in, and that in the case of the decrease it did not allow more than a certain quantity of the ion to go out. It thus seems as if the permeability of the surface were adjusted to a certain minimum and to a certain maximum of every single ion or salt, the permeability being stopped from within to without, whenever the minimum, and from without to within, whenever the maximum is reached in the cell sap; both irrespective of proper physical osmotic equilibrium (“Physiologisches Gleichgewicht”). Thus, in fact, there only would be a case of primary regulation, nothing more. It would all appear rather similar to what occurs in the kidney. Of course we do not assert that our explanation is right, but it is possible and is at the same time the most simple, and it is our general practice always to prefer the most simple hypotheses.98Many fishes are able to withstand great changes in the osmotic pressure of sea-water; the osmotic pressure of their body fluids, though never in a real physical equilibrium with the pressure of the medium, nevertheless may vary whenever the abnormal conditions of the latter exceed certain limits.99See Stahl,Naturw. Wochenschrift, N. F. 5, 1906, No. 19.100Arch. Anat. Phys., Phys. Abt. Suppl., 1902.101The adaptive phenomena discovered by Gaidukow depend upon a real alteration in the formation of pigments. In the (primary) chromatic adaptation of pupae of Lepidoptera with respect to the colour of the ground they live upon, we only have the variable effects of pre-established chromatophores (Poulton,Phil. Trans. London, 178 B, 1888; Merrifield,Trans. Ent. Soc. London, 1898). The same holds for chromatic adaptations in crabs (Gamble and Keeble,Quart. Journ. Micr. Sci.43, 1900; Minkiewicz,Arch. Zool. exp. et gén.sér. 4, 7, notes, 1907).102The theory of oxidation we have shortly sketched here was developed in chapter B. 5, of myOrganische Regulationen. Recent discoveries of Winterstein’s (Zeitschr. allg. Physiol.6, 1907) have given the strongest support to my hypothetic statements, and, in fact, can be said to have brought the doctrine of organic oxidation to a critical point. There can be no doubt that oxygen not only plays the “antipoisonous” rôle I had assigned to it, but that it is not even of such great importance for the supply of functional energy as former times had assumed. No doubt it serves to drive the functional machine, but decomposition of certain chemical constituents of the organism serves this purpose even more. The latter does so in the most fundamental and original manner, so to speak, whilst oxidation only burns up its products. Almost all elemental functions, in nerve-tissue at least, go on very well in the absence of oxygen, provided that certain “poisonous” substances, resulting from this anaërobic metabolism, are constantly removed. In normal conditions that is done by oxygen, and in doing so oxygen certainly assists the supply of energy, but it does not furnish the whole of it. The difference between so-called “aërobic” and “anaërobic” life almost completely disappears under such a view, and many so-called “regulations,” of course, disappear at the same time; there is no more “intramolecular respiration.”103But nevertheless albumen is not to be replaced altogether in vertebrates by fat or carbohydrate; it probably serves some special function besides combustion, even in the adult.104Arch. Entw. Mech.18, 1904.105To a physiological friend of mine I owe the suggestion that it is the permanently functioning tissues which stand hunger better than the others, at least if the sexual cells might be regarded as capable of asécrétion internein all cases. Then the adaptations in the state of hunger might be said to be reduced in some degree to “functional adaptation.” But it must remain an open question, it seems to me, whether such a view may indeed hold in the face of the facts observed inPlanariaand infusorians.106In all cases where fungi of the same species are able to live on different hosts, that is, to penetrate membranes of a different chemical character, a similar objection as to the “secondary” type of such a regulation may be made.107The discovery of Weinland that adult dogs are able to produce “lactase” in their pancreas, whenever they are fed, quite abnormally, with milk-sugar, has recently been said to be vitiated by an analytical mistake.108Compare the excellent review of the subject by Bayliss and Starling in theErgebnisse der Physiologie, 5, 1906, p. 664. The reader who misses here an analysis of the brilliant discoveries of Pawlow and his followers, relating to so-called “psychical and associative secretion,” will find these facts dealt with in another section of the book. These facts, indeed, would prove vitalism, it seems to me.109It would be a true secondary metabolic regulation, if after the extirpation of one gland another different one were to assume its function. Nothing is known in this respect except a few rather doubtful observations about the interchange of functions between thymus and thyroid, except also the fact that the so-called lymph-glands increase in size after the extirpation of the spleen. Even here, of course, a sort of “restitution” would be included in adaptation proper.110A good review is given by E. Fromm,Die chemischen Schutzmittel des Tierkörpers bei Vergiftungen, Strassburg, 1903.111Davenport,Arch. Entw. Mech.2, 1895–1896, and Hausmann,Pflüger’s Arch.113, 1906.112Leçons sur la pathologie comparée de l’inflammation, Paris, 1902.113The other steps or phases in the process of inflammation have also been regarded as adaptive: the increased quantity of body fluid for instance is said to serve to dilute poisonous substances.114See Jacoby,Immunität und Disposition, Wiesbaden, 1906.115Collected Studies on Immunity by Ehrlich and his Collaborators, translated by Ch. Bolduan, New York and London, 1906.116So-called genuine or innate immunity, in contrast to the immunity which is acquired, is of course a case of adaptedness only and not of adaptation. There also exists a high degree of specific adaptedness in some animals with regard to their faculty of coagulating blood. (See Leo Loeb,Biol. Bull.9, 1905.)117We cannot do more than barely mention here the problem of the localisation of anti-body production. In general it seems to be true that anti-bodies are produced by those cells which require to be protected against toxins; that would agree with the general rule, that all compensation of the change of any functional state proceeds from the part changed in its function.118Here again I should like to except from this statement the discoveries of Pawlow. See page204, note108.119The few cases of an “improvement” of morphogenetic acts in hydroids described by myself are too isolated at present to be more than mere problems (Arch. Entw. Mech.5, 1897). The same is true, it seems to me, with regard to certain recent discoveries made by R. Pearl onCeratophyllum(Carnegie Inst. Wash. Publ.No. 58, 1907); and by Zeleny on a medusa (Journ. exp. Zool.5, 1907). Pawlow’s discovery, that the enzymotic composition of the pancreatic fluid in dogs becomes more and more adapted to a specific composition of the food (either meat or bread and milk) the longer such a specific composition is offered to the individual animal, may probably be understood as a case of mere functional adaptation of the cells of the digestive glands, if it stands criticism at all (see Bayliss and Starling,Ergeb. Physiol.5, 1906, p. 682).120Experiments carried out in the “Biologische Versuchsanstalt” at Vienna indeed have shown that many animal types are capable of at least a certain degree of restitution, although they had previously been denied this faculty by zoologists.121Ueber das Gedächtnis als eine allgemeine Function der organischen Materie, Wien, 1870. New edition inKlassiker d. exakt. Wiss., Leipzig, Engelmann.122Die Mneme, Leipzig, 1904.123Driesch,Organ. Regul.1901.124The “ideal whole” is also proved to exist, if anygiven“Anlage,” say of a branch, is forced to give origin to a root, as has really been observed in certain plants. This case, like many other less extreme cases of what might be called “compensatory heterotypy,” are best to be understood by the aid of the concept of “prospective potency.” It is very misleading to speak of a metamorphosis here. I fully agree with Krašan about this question. See also page112, note48, and myOrgan. Regul.pp. 77, 78.125Winkler has discovered the important fact, that the adventitious buds formed upon leaves may originate either from one single cell of the epidermis or from several cells together; a result that is very important with respect to the problem of the distribution of “potencies.”126The “regeneration” of the brain of annelids for instance is far better regarded as an adventitious formation than as regeneration proper: nothing indeed goes on here at the locality of the wound; a new brain is formed out of the ectoderm at a certain distance from it.127A full “analytical theory of regeneration” has been developed elsewhere (Organ. Regul.p. 44, etc.). I can only mention here that many different problems have to be studied by such a theory. The formation of the “Anlage” out of the body and the differentiation of it into the completely formed results of regeneration are two of them. The former embraces the question about the potencies not only of the regenerating body but of the elements of the Anlage also; the latter has to deal with the specific order of the single acts of regenerative processes.128And, of course, at the root of every new starting of certain parts of morphogenesis also, as in regeneration and in adventitious budding; these processes, as we know, being also founded upon “complex-equipotential systems,” which have had their “genesis.”129New edition in the “Klassiker d. exakt. Wiss.” Leipzig, Engelmann; see also Bateson,Mendel’s Principles of Heredity, Cambridge, 1902.130For the sake of simplicity I shall not deal here with those cases of hybridisation in which one quality is “recessive,” the other “dominant,” but only allude to the cases, less numerous though they be, where a real mixture of maternal and paternal qualities occurs.131This hypothesis was first suggested by Sutton and is at present held by orthodox Mendelians; but probably things are a little more complicated in reality, as seems to be shown by some facts in the behaviour of so-called “extracted recessives.” In Morgan’sExperimental Zoology, New York, 1907, a full account of the whole matter is given.132Arch. Entw. Mech.21, 22, and 24, 1906–7; see also Doncaster,Phil. Trans. Royal Soc.London, B. 196, 1903. The influence of different temperature upon the organisation of the hybrids is not always quite pure, inasmuch as the paternal and the maternal forms may themselves be changed by this agent. In spite of that there exists an influence of the temperature upon the hybridas such, at least with regard to certain features of its organisation.133Only the nucleus of the egg had entered its first stages of activity.134The first proof of vitalism, indeed, rests upon the analysis of the differentiation of an harmonious-equipotential system as awhole: thiswholecannot be a machine that would relate to differentiation as awhole; the question whether there might be any machines distributedinthe whole, in the form of the nuclei is of no importance at all in this argument. Moreover the pressure experiments (see page63) prove the unimportance of such “machines” for the specificity of differentiation, and the second proof of vitalism shows that the nuclei cannot be regarded as machines accounting for differentiation inanyway.135Boveri tried to fertilise enucleated fragments of the egg ofSphaerechinuswith the sperm ofEchinus. He failed to get any results in isolated experiments, but found a few small larvae of the pureEchinustype in large cultures consisting of shaken eggs. But later experiments on hybridisation in sea-urchins have shown that a full hybrid ofEchinusandSphaerechinusmay be purely paternal also.136Surely the new results of Herbst, mentioned above, are another indication of the importance of something in the nucleus. The first stage in parthenogenesis, which he used in his experiments, is a nuclear phenomenon.137Boveri (Ergebn. üb. d. Konstitution etc. des Zellkerns, Jena, 1904; and “Zellen-Studien VI.”Jen. Zeitschr.43, 1907) has made it highly probable by experiments that the different chromosomes of the nucleus of the sexual products play a different part in morphogenesis, though not in the sense of different single representatives of different single organs. This doctrine, of course, would not alter the whole problem very much: the chromosomes would only bemeansof morphogenesis and nothing else, no matter whether they were of equal or of different formative value. It only is with regard to the problem of the determination of sex (see page107, note46), that the morphogenetic singularity ofonecertain specific chromosome can be said to be proved.138H. M. Vernon,Variations in Animals and Plants, London, 1903.139De Vries,Die Mutationstheorie, i., 1901; and Klebs,Jahrb. wiss. Bot.42, 1905.140They would not be “real exceptions” if Klebs (Arch. Entw. Mech.24, 1907) were right in saying that both variations and mutations owe their existence to external agents. What is reallyprovedby Klebs is the possibility of changing thetypeof a curve of variation and of provoking certain discontinuous varieties by external means. See also Blaringhem (Comptes rend.1905–6, andSoc. de Biol.59, 1905), and MacDougal (Rep. Depart. Bot. Res., 5th Year-book Carnegie Inst., Washington, 129).141H. de Vries,Species and Varieties: their Origin by Mutation, London, 1905. A short review of the “mutation-theory” is given by Francé inZeitschrift f. d. Ausbau d. Entwickelungslehre, i. 1907. It is well known that Gautier, and, in the first place, Korshinsky, advocated a similar view previous to the authors named in the text.142Recent years have created the beginnings of a systematics based on chemical differences of metabolism and its products: such differences in fact have been found to go hand in hand with diversities of the type in some cases (v. Bunge, Przibram, etc.).143We prefer this unpretending definition of the theory of descent to every other. As soon as one introduces into the definition the concept of the “transmutability of species,” the term “species” would require a special definition, and that would lead to difficulties which it is unnecessary to deal with for our main purposes. It has been remarked by Krašan, (Ausichten und Gespräche über die individuelle und specifische Gestaltung in der Natur) and by several other writers, that the problem of mutability or immutability of course relates to the individuals in the first place. I should like to add to this remark that the possibility must be admitted of the individuals being transmutable, whilst the “species” are not transmutable at the same time, the line of the “species” being a fixed order, through which the “individuals” have to pass in the course of their generations. What is meant here will become clearer, when we study the different possible aspects of “phylogeny.”144It seems to me that my argument gives a broader logical basis to the theory of descent than does that of G. Wolff (Die Begründung der Abstammungslehre, München, 1907). Wolff starts from the concept of organic teleology, and thus finds the only reason for accepting the theory of transformism in the existence of so-called “rudimentary organs”; these organs would form an obstacle to teleology if they could not be regarded as inherited.145See Wigand,Der Darwinismus und die Naturforschung Newton’s und Cuvier’s, Braunschweig, 1874–7; Nägeli,Mechanisch-physiologische Theorie der Abstammungslehre, München, 1884; G. Wolff,Beiträge zur Kritik der Darwin’schen Lehre, 2nd ed. Leipzig, 1898; etc.146Darwinismus und Lamarckismus, München, 1905.147This would not be true, if the varieties of plants produced by Blaringhem, Klebs, and MacDougal by means ofexternalagents were really “mutations” (comp. page 238, note 3).148Of course, the inheritance of mutations would imply a certain sort of “inheritance of acquired characters,” on the condition stated in the preceding note. But, probably, the germs of the next generation might be regarded here as being directly affected by the external agent, in a manner that will briefly be mentioned later on in the text.149Comp. page 238, note 2.150Certain English authors have applied the term “modification” to all kinds of organic properties acquired from without, whether they are adapted or not.151Of course the inheritance of specific values from the results of fluctuating variations, leading to new averages of variability (see p.265), may also be understood in this manner, the conditions of nourishment acting upon the adult and upon its germs equally well.152Berichte üb. d. Sitzung. d. Ges. f. Bot., Hamburg, 1887, 3 Heft.153Quite recently Kammerer (Arch. Entw. Mech.25, 1907, p. 7) has published very important experiments on the inheritance of “acquired” modifications with regard to the peculiarities of reproduction inSalamandra atraandS. maculosa. It seems rather improbable—though not absolutely impossible—that the germ cells were directly affected by the external modifying agent in this case.154We have not spoken about the hypothetic inheritance of pure physiological adaptations, for it is clear without further discussion that innate specific immunity, for instance, being a specific “adaptedness” (seep.186)mightbe due to the inheritance of the results of active immunity as an adaptation, just as adaptive congenital structuresmightbe due to such an inheritance.155C. E. v. Baer clearly discriminated between the type, the degree of organisation, and the histological structure. All these three topics indeed have to be taken into account separately; the third alone is of the adaptive type. All of them may be independent of each other: the Amoeba may be as adapted histologically as is a high vertebrate, but it is of much lower type; and in its own type it is of a lower degree of organisation than Radiolaria are.156I repeat once more that we are dealing here with dogmatic “Neo-”Lamarckism exclusively. This theory indeed claims to explainallfeatures and properties of organic bodies on the basis of the feeling of needs and storing of contingent fulfilments and on this basis alone, just as dogmatic “Neo”-Darwinism claims to account forallthose phenomena on the ground of contingent variations and natural selection. Darwin himself, as we have seen, intentionally left unexplained certain primary features of life and therefore cannot be blamed for having failed to explain them, though even then his theory remains wrong. Lamarck personally considered a real primary organisatory law of phylogeny as being of fundamental importance, and therefore he is not in the least responsible if “Neo-Lamarckism” fails as a universal theory.157Compare also the excellent criticism of Lamarckism lately given by G. Wolff,Die Begründung der Abstammungslehre, München, 1907.158It has also very often been said by Darwinians that Lamarckism is only able to explain those cases of adaptedness which relate to active functioning but not mere passive adapted characters, like “mimicry” for example. But this argumenttaken by itself, it seems to me, would not be fatal to Neo-Lamarckism in the special form August Pauly gave to this doctrine.159But nothing more. All “mutations” hitherto observed in nature or (comp. page 238, note 3) experimentally produced relate only to “varieties” and not to “species.” One could hardly say that the recent investigations about the production of mutations byexternalmeans have strengthened their importance for the general theory of transformism.160The word “possible” relating to originating, of course, not to surviving. It is here that natural selection may acquire its logical importance alluded to above (see page264).161The discussions in the second volume of this book will show the possible significance of such an analysis. We at present are dealing with entelechy in a quasi-popular manner.162See pp.26,45,54, etc.163An immanent vitalistic phylogenywithouta pre-established end has recently been advocated by H. Bergson (L’évolution créatrice, Paris, 1907).164In this connection the problem may be raised, whether there can be such a thing as unchangeable “species” in spite of the mutability of the individuals. Compare page 251, note 1.165On account of the limited size of the earth a certain final stage of human civilisation might be expected in a future time; but it would be the size of the earth which determined this end, and not the process of civilisation itself.166Die Grenzen der naturwissenschaftlichen Begriffsbildung, Tübingen and Leipzig, 1902.167The word “universality” to be understood here in quite an unpretentious quasi-popular meaning, not strictly epistemologically.168To avoid mistakes I wish to say here most emphatically that, according to Rickert, the method of history is regarded as completelyfreefrom subjectivity as soon as its “values” are onceestablished. But this cannot avail to save the theory.169This is a rather optimistic conception of “history.” Personally, I must confess that even its emotional and practical importance seems to me to be at least diminished by the retarding effects which all sorts of “historical” considerations—in science as well as in arts and in public life—carry with them. All real progress is non-historical—and its champions almost always have become martyrs: this fact seems not to recommend history as a means of education, except for persons of a very strong character.

1Windelband (Geschichte und Naturwissenschaft, 3 Auflage, 1904) gives the name “nomothetic” to the whole of our “science” and calls the method of history “idiographic.” We thought it better to establish three fundamental types of all possible branches of knowledge.

2See J. Arth. Thomson,The Science of Life, London, 1899.

3E. B. Wilson,The Cell in Development and Inheritance, New York, Macmillan, 1896.

4Amer. Journ. Physiol.vols. iii. and iv. 1900.

5According to Delage (Arch. Zool. exp., 3 sér. 10, 1902), it is indifferent for the realisation of artificial parthenogenesis, whether but one, or both, or neither of the “polar bodies” has been formed. But the egg must be in the first stages of maturation to the extent that the “nuclear membrane” must be already dissolved.

6The older theories, attributing to fertilisation (or to “conjugation,”i.e.its equivalent in Protozoa), some sort of “renovation” or “rejuvenescence” of the race, have been almost completely given up. (See Calkins,Arch. für Entwickelungsmechanik, xv. 1902). R. Hertwig recently has advocated the view, that abnormal relations between the amounts of nuclear and of protoplasmatic material are rectified in some way by those processes. Teleologically, sexual reproduction has been considered as a means of variability (Weismann), but also as a means of preserving the type!

7The phrase “ceteris paribus” has to be added of course, as the duration of each single elementary morphogenetic process is liable to vary with the temperature and many other conditions of the medium.

8We shall not avoid in these lectures the word “explain”—so much out of fashion nowadays. To “explain” means to subsume under known concepts, or rules, or laws, or principles, whether the laws or concepts themselves be “explained” or not. Explaining, therefore, is always relative: what is elemental, of course, is only to be described, or rather to be stated.

9Das Keimplasma, Jena, 1892.

10Die Bedeutung der Kernteilungsfiguren, Leipzig, 1883.

11Unsere Körperform, Leipzig, 1875.

12Die Entwickelungsgeschichte der Unke, Leipzig, 1875.

13Gesammelte Abhandlungen, Leipzig, 1895. Most important theoretical papers:—Zeitschr. Biolog.21, 1885;Die Entwickelungsmechanik der Organismen, Wien, 1890;Vorträge und Aufsätze über Entwickelungsmechanik, Heft i., Leipzig, 1905.

14Virchow’s Archiv.114, 1888.

15Zeitschr. wiss. Zool.53, 1891.

16Zeitschr. wiss. Zool.55, 1892.

17In the pressure experiments I had altered the relative position of the nucleiin origine. In later years I succeeded in disturbing the arrangement of the fully formed cells of the eight-cell stage, and in getting normal larvæ in spite of that in many cases. But as this series of experiments is not free from certain complications—which in part will be understood later on (see page73)—it must suffice here to have mentioned them. (For further information see my paper inArchiv. f. Entwickelungsmechanik, xiv., 1902, page 500.)

18Mitteil. Neapel. 11, 1893.

19But the elementary magnets would have to be bilateral!

20Arch. Entw. Mech.2, 1895.

21Anat. Anz.10, 1895.

22Arch. Entw. Mech.3, 1896.

23It deserves notice in this connection, that in some cases the protoplasm of parts of a germ has been found to be more regulable in the earliest stages, when it is very fluid, than later, when it is more stiff.

24Compare myAnalytische Theorie der organischen Entwickelung, Leipzig, 1894, and my reviews inErgebnisse der Anatomie und Entwickelungsgeschichte, vols. viii. xi. xiv., 1899–1905. A shorter review is given inErgebnisse der Physiologie, vol. v., 1906. The full literature will be found in these reviews.

25If the plane of section passes near the equator of the germ, two whole larvae may be formed also, but in the majority of cases the “animal” half does not go beyond the blastula. The specific features of the organisation of the protoplasm come into account here. See also page65, note17.

26A change of the position of the cell is of course effected by each variation of the direction of the cut, which is purely a matter of chance.

27The reader will remember (see page65, note17), that even the germ of Echinus is not quite equipotential along its main axis, but it is equipotential in the strictest sense around this axis. The germs of certain medusae seem to be equipotential in every respect, even in their cleavage stages.

28Journ. Exp. Zool.1, 1904.

29Great caution must be taken in attributing any specific morphogenetic part to differently coloured or constructed materials, which may be observed in the egg-protoplasm in certain cases. They may play such a part, but in other cases they certainly do not (see Lyon,Arch. Entw. Mech.23, 1907). The final decision always depends on experiment.

30It seems that these physical conditions also—besides the real specifications in the organisation of the egg—may be different before and after maturation or (in other cases) fertilisation. (See Driesch,Archiv f. Entwickelungsmechanik, 7, p. 98; and Brachet,ibid.22, p. 325.)

31Studien über Protoplasmamechanik, Leipzig, 1886.

32Unters. üb. mikroskopische Schäume und das Protoplasma, Leipzig, 1892.

33Jena. Zeitschr.26, 1892.

34According to Zur Strassen’s results the early embryology ofAscarisproceeds almost exclusively by cellular surface-changes: the most typical morphogenetic processes are carried out by the aid of this “means.” As a whole, the embryology ofAscarisstands quite apart and presents a great number of unsolved problems; unfortunately, the germ of this form has not been accessible to experiment hitherto.

35Rhumbler has recently published a general survey of all attempts to “explain” life, and morphogenesis in particular, in a physico-chemical way (“Aus dem Lückengebiet zwischen organismischer und anorganismischer Natur,”Ergeb. Anat. u. Entw.-gesch.15, 1906). Thisvery pessimisticsurvey is the more valuable as it is written by a convinced “mechanist.”

36Compare the analytical discussions of Klebs, to whom we owe a great series of important discoveries in the field of morphogenetic “means” in botany. (Willkürliche Entwickelungsänderungen bei Pflanzen, Jena, 1903; see alsoBiol. Centralblatt, vol. xxiv., 1904, and my reply to Klebs,ibid.23, 1903.)

37Arch. Entw. Mech.17, 1904.

38Zeitschr. wiss. Zool.55, 1902; andMitt. Neapel.11, 1903.

39In certain cases part of the specific feature of the process in question may also depend on the “cause” which is localising it,e.g.in the galls of plants.

40Herbst, “Ueber die Bedeutung die Reizphysiologie für die kausale Auffassung von Vorgängen in der tierischen Ontogenese” (Biol. Centralblatt, vols. xiv., 1894, and xv., 1895);Formative Reize in der tierischen Ontogenese, Leipzig, 1901. These important papers must be studied by every one who wishes to become familiar with the subject. The present state of science is reviewed in my articles in theErgebnisse der Anatomie und Entwickelungsgeschichte, vols. xi. and xiv., 1902 and 1905.

41Compare the important papers by J. Loeb,Untersuchungen zur physiologischen Morphologie der Tiere, Würzburg, 1891–2.

42I use the word “primordia” for the German “Anlage”; it is better than the word “rudiment,” as the latter may also serve to signify the very last stage of a certain formation that is disappearing (phylogenetically).

43A full analysis of the subject would not only have to deal with formative stimuli as inaugurating morphogenetic processes, but also with those stimuli which terminate or stop the single acts of morphogenesis. But little is actually known about this topic, and therefore the reader must refer to my other publications. I will only say here, that the end of each single morphogenetic act may either be determined at the very beginning or occur as an actual stopping of a process which otherwise would go on for ever and ever; in the first case some terminating factors are included in the very nature of the morphogenetic act itself.

44A full account of the present state of the subject will be found in Morgan’sExperimental Zoology, New York, 1907.

45But there certainly exist many formative relations between the real sexual organs and the so-called secondary sexual characters. Herbst has given a full analytical discussion of all that is known on this subject; but the facts are much more complicated than is generally supposed, and do not lend themselves therefore to short description. See also Foges,Pflüger’s Arch.93, 1902.

46It seems that in some cases (Dinophilus, certain Arthropods) the sexual products are invariably determined as “arrenogennetic” or as “thelygennetic” (Wilson,Journ. Exp. Zool.ii. and iii. 1905–6), whilst in others (Amphibia) the state of maturation or “super”-maturation determines the sex of the future organism (R. Hertwig,Verh. D. Zool. Ges.1905–7).

47Driesch,Die organischen Regulationen, Leipzig, 1901; Morgan,Regeneration, New York, 1901.

48But real compensatory differentiation occurs in the cases of so-called “hypertypy” as first discovered by Przibram and afterwards studied by Zeleny: here the two organs of a pair show a different degree of differentiation. Whenever the more specialised organ is removed the less developed one assumes its form. Similar cases, which might simply be called “compensatory heterotypy,” are known in plants, though only relating to the actual fate of undifferentiated “Anlagen” in these organisms. A leaf may be formed out of the Anlage of a scale, if all the leaves are cut off, and so on.

49For a fuller analysis compare my opening address delivered before the section of “Experimental Zoology” at the Seventh Zoological Congress, Boston, 1907: “The Stimuli of Restitutions” (see Proceedings of that Congress).

50The problem of the stimulus of a secondary restitution as a whole must not be confused with the very different question, what the single “formative stimuli” concerned in the performance of a certain restitutive act may be. With regard to restitution as awholethese single “formative stimuli” might properly be said to belong to its “internal means”—in the widest sense of the word.

51T. H. Morgan is very right in stating that, in regeneration, the “obstacle” itself is newly formed by the mere process of healing, previous to all restitution, and that true restitution happens all the same.

52I merely mention here the still “simpler” one—applicable of course to regeneration proper exclusively—that for the simple reason of being “wounded,”i.e.being a surface open to the medium, the “wound” brings forth all that is necessary to complete the organism.

53That compensatory hypertrophy cannot be due to “functional adaptation”—to be analysed later on—was proved by an experiment of Ribbert’s. Compensation may occur before the function has made its appearance, as was shown to be the case in the testicles and mammae of rabbits. (Arch. Entw. Mech.1, 1894, p. 69.)

54At any given time only the absolute size of the regenerated part is greater in animals which are well fed; the degree of differentiation is the same in all. Zeleny has found that, if all five arms of a starfish are removed, each one of them will regenerate more material in a given time than it would have done if it alone had been removed. But these differences also only relate to absolute size and not to the degree of differentiation. They possibly may be due in fact to conditions of nourishment, but even here other explanations seems possible (Zeleny,Journ. exp. Zool.2, 1905).

55For a good discussion of “super-regeneration” in the roots of plants see Němec,Studien über die Regeneration, Berlin, 1905. Goebel and Winkler have succeeded in provoking the “restitution” of parts which were not removed at all by simply stopping their functions (leaves of certain plants were covered with plaster, etc.). (Biol. Centralbl.22, 1902, p. 385;Ber. Bot. Ges.20, 1902, p. 81.) A fine experiment is due to Miehe. The algaCladophorawas subjected to “plasmolysis,” each cell then formed a new membrane of its own around the smaller volume of its protoplasm; after that the plants were brought back to a medium of normal osmotic pressure, and then each single cell grew up into a little plant (all of them being of the same polarity!). Two questions seem to be answered by this fact: loss of communication is of fundamental importance to restitution, and the removal of mechanical obstacles plays no part in it, for the mechanical resistances were the same at the end of the experiment as they had been at the beginning. (Ber. Bot. Ges.23, 1905, p. 257.) For fuller analysis of all the problems of this chapter see my Organische Regulationen, my reviews in theErgebnisse der Anatomie und Entwickelungsgeschichte, vols. viii. xi. xiv., and my Boston address mentioned above. Compare also Fitting,Ergebn. d. Physiol.vols. iv. and v.

56The so-called “inner secretion” in physiology proper would offer a certain analogy to the facts assumed by such an hypothesis. Compare the excellent summary given by E. Starling at the seventy-eighth meeting of the German “Naturforscherversammlung,” Stuttgart, 1906.

57The name of singular-equipotential systems might also be applied to elementary organs, the single potencies of which are awaked to organogenesis by specific formative stimuli from without; but that is not the case in the systems studied in this chapter.

58The distance of the other boundary line fromaorbwould be given by the value ofs.

59A far more thorough analysis of this differentiation has been attempted in my paper, “Die Localisation morphogenetischer Vorgänge. Ein Beweis vitalistischen Geschehens,” Leipzig, 1899.

60This statement isnot strictlycorrect forTubularia. I found (Archiv f. Entwickelungsmechanik, ix. 1899), that a reduction of the length of the stem is always followed by a reduction of the size of the hydranth-primordium, but there is no real proportionality between them. It is only for theoretical simplification that a strict proportionality is assumed here, both in the text and the diagram. But there is an almost strict proportionality in all cases of “closed forms.”

61One might object here that in a piece of aTubulariastem, for instance, the tissues are in direct contact with the sea-water at the two points of the wounds only, and that at these very points a stimulus might be set up—say by a process of diffusion—which gradually decreases in intensity on its way inward. And a similar argument might apply to the small but whole blastula of Echinus, and to all other cases. But, in the first place, stimuli which only differ in intensity could hardly call forth the typical and typically localised single features realised in differentiation. On the other hand—and this will overthrow such an hypothesis completely—the dependence of the single localised effects in every case on theabsolute sizeof the fragment or piece chosen for restoration renders quite impossible the assumption that all the singularities in the differentiation of the harmonious systems might be called forth by single stimuli originating in two fixed places in anindependentway. These would never result in any “harmonious,” any proportionate structure, but a structure of the “normal” proportionalityand sizeat its two ends and non-existent in the middle!

62See my article inBiolog. Centralblatt, 27, 1907, p. 69. The question is rendered still more complicated by the fact that in the case of the regeneration, say, of a leg it is not the original “morphogenetic compound” which is again required for disintegration, after it has become disintegrated once already, but only a specific part of it: just that part of it which is necessary for producing the leg! On the other hand, it would be impossible to understand, on the basis of physical chemistry, how the isolated branchial apparatus ofClavellinacould be transformed, by chemical processes exclusively, into a system of which only a certainpartconsists of that substance of which the starting-point had been composed in itscompleteness.

63Besides the specified poles determined by the polar-bilateral structure of the protoplasm.

64The pressure experiments and the dislocation experiments come into account here; for the sake of simplicity they have not been alluded to in the main line of our argument.

65My “first proof of vitalism” was first developed in the paper, “Die Localisation morphogenetischer Vorgänge,” Leipzig, 1899. (See additional remarks inOrganische Regulationem, Leipzig, 1901, and inArchiv für Entwickelungsmechanik, 14, 1902.) I cannot admit that any really serious objection has been brought forward against it. (See my articles inBiologisches Centralblatt, 22, 23, 27, and inErgebnisse d. Anat. u. Entwickelungsgesch. 11, 14.) An historical sketch of vitalism will be found in my book,Der Vitalismus als Geschichte und als Lehre, Leipzig, 1905.

66We are dealing here with morphogenesis and so-called vegetative physiology only; to certain psychologists, who have refuted the theory of psycho-physical parallelism, I must grant that they also have proved vitalism. (See Volume II.)

67The eight larvae would be incomplete in some respect, but not with regard to symmetry. They would be “whole” ones, only showing certain defects in their organisation. See page65note17, and page73.

68Reciprocal harmony may be reduced in some cases to the given proportions of one original harmonious system, from which the single constituents of the complicated system, showing reciprocal harmony, are derived. Then we have only an instance of “harmony of constellation” (see p.109). But reciprocal harmony seems to become a problem itself, if it occurs in restitutions starting from quite a typical point, selected by the experimenter. It will be a problem of future research to give an exact formula of what happens here. Reciprocal harmony also occurs in regeneration proper. It is known that the formation of the regenerative bud and the differentiation of this bud follow each other. As the bud is composed of different elementary systems, it follows that these different systems, of which every single one is harmonious, also have to work in reciprocity to each other, in order that one whole proportionate formation may result.

69Biol. Centralblatt.23, 1903.

70Certain phenomena of the physiology of growth ofGeranium Robertianum, recently discussed by Francé from a vitalistic point of view (Zeitschr. Entw. lehre. 1, 1907, Heft iv.), might also belong here. I cannot see an independent proof of vitalism in these facts if taken by themselves; a pre-existing “machine” cannot be absolutely excluded here.

71Driesch,Arch. Entw. Mech.5, 1897.

72Driesch,Arch. Entw. Mech.14, 1902.

73The root may be restored by regeneration proper, or by the production of adventitious roots, or by one of the side-roots changing its geotropism from horizontal to positive, according to the smaller or greater distance of the wound from the tip.

74“Retro”-differentiation, of course, is not “Re”-differentiation (“Umdifferenzierung,” see p.111), though it may help it to occur.

75Of course such a real decay of parts may happen in other cases.

76Certain cases of retro-differentiation occurring under conditions of strict fasting will be described in a later chapter.

77Klebs has suppressed the reproductive phase of organisation altogether, in fungi as well as in flowering plants, or has made it occur abnormally early, merely by changing the “external conditions” and by altering the “internal” ones correspondingly. There is hardly anything like an adaptation in these cases, which, by the way, offer certain difficulties to analysis, as the boundaries between “cause” and “means” are not very sharp here.

78Compare Herbst,Biol. Centralbl.15, 1895; and Detto,Die Theorie der direkten Anpassung, Jena, 1904. A full account of the literature will be found in these papers.

79Vöchting (Jahrb. wiss. Bot.34, 1899) forced the bulbs of plants to become parts of the stem, and parts of the stem to form bulbs; in both cases the most characteristic changes in histology could be observed, being in part adaptations, but in part restitutions of the proper type. (See also myOrganische Regulationen, 1901, p. 84.) A true and simple instance of a “secondary adaptation” seems to be furnished in a case described by Boirivant. InRobiniaall the leaflets of a leaf-stalk were cut off: the leaf-stalk itself then changed its structure in order to assist assimilation, and also formed real stomata.

80Arch. Entw. Mech.17, 1904.

81Roux,Gesammelte Abhandlungen, vol. i. 1895; in particular,Der Kampf der Teile im Organismus, Leipzig, 1881.

82Arch. Entw. Mech.21, 1906. By a very detailed comparative study Babák was able to prove that it is the plant proteids to which the effect of vegetable food is chiefly due; thus we have an adaptation to digestibility. Mechanical circumstances are only of secondary importance. (See also Yung.)

83Atrophy of muscles by inactivity is not to be confused with atrophy by cutting the motor nerve; the latter is very much more complete.

84Loeb has advocated the view that the “adaptive” growth of working muscles is simply due to the presence of a greater number of molecules in their protoplasm, muscular activity being generated by a process of chemical decomposition.

85What has been reallyprovedto exist by the very careful studies carried out by Child, is only certain cases of functional adaptation to mechanical conditions of the strictest kind, and relating to the general mobility only, but nothing more; such adaptations can be said to accompany restitution. See, for instance,Journ. exp. Zool.3, 1906, where Child has given a summary of his theory.

86Even in Vöchting’s experiments (see page174, note79), in which adaptations are mixed with true restitutions in the closest possible manner, a few phenomena of the latter type could most clearly be separated. The stimulus which called them forth must have been one of the hypothetic sort alluded to in a former chapter (see page113). The best instances of true restitutions were offered in those cases, where, after the removal of all the bulbs, typical starch-storing cells were formed without the presence of any starch.

87Beiträge zur Lehre von den Functionen der Nervencentren des Frosches, Berlin, 1869.

88The “secondary adaptations” observed by Vöchting are too complicated and too much mingled with restitutions to allow any definite analysis of the fact of the “secondary adaptation” as such.

89General literature: Fröhlich,Das natürliche Zweckmüssigkeitsprincip in seiner Bedeutung für Krankheit und Heilung, 1894. Driesch,Die organischen Regulationen, 1901. A. Tschermak, “Das Anpassungsproblem in der Physiologie der Gegenwart,” in a collection of papers in honour of J. P. Pawlow, St. Petersburg, 1904. Bieganski, “Ueber die Zweckmässigkeit in den pathologischen Erscheinungen,”Annal. d. Naturphil.5, 1906. Among the general text-books of physiology those by Pfeffer (Pflanzenphysiologie, 1897–1904) and von Bunge (Lehrbuch d. Phys. d. Menschen, 1901) are the fullest on the subject of “regulations.” See also different papers on general pathology by Ribbert.

90According to investigations of the last two years, the physics of colloids seems to play as important a part in physiology as osmosis does; we here meet “means” of functioning just as we have already had “means” of organogenesis.

91I only mention here that certain modern psychologists have assigned the true law of Weber to the sphere of judgment and not of sensation. If applied to objective reactions only, in their dependence on objective stimuli, it, of course, becomes less ambiguous, and may, in a certain sense, be said to measure “acclimatisation” with regard to the stimulus in question. The mathematical analogy of the law of Weber to the most fundamental law of chemical dynamics seems very important.As to “acclimatisation” in the more usual meaning of the word, with regard to a change of the general faculty of resisting certain agents of the medium, “immunity” proper is to form a special paragraph of what follows, and to “acclimatisation” towards different degrees of salinity (in algae or fishes) some special remarks will also be devoted on a proper occasion. There remains only “acclimatisation” to different temperatures; but on this topic not much more than the fact is known (see Davenport,Arch. f. Entw. Mech.2, p. 227). “Acclimatisation” does not allow of a sharp general definition; it may be the result of verydifferentkinds of adaptations in our sense of the word.

As to “acclimatisation” in the more usual meaning of the word, with regard to a change of the general faculty of resisting certain agents of the medium, “immunity” proper is to form a special paragraph of what follows, and to “acclimatisation” towards different degrees of salinity (in algae or fishes) some special remarks will also be devoted on a proper occasion. There remains only “acclimatisation” to different temperatures; but on this topic not much more than the fact is known (see Davenport,Arch. f. Entw. Mech.2, p. 227). “Acclimatisation” does not allow of a sharp general definition; it may be the result of verydifferentkinds of adaptations in our sense of the word.

92I should think that the problem of the re-establishment of irritability, in principle at least, arises even when there is not a trace of so-called “fatigue” or of a “refractory period.” The process of restoring may be so rapid as not to be noticeable, nevertheless some sort of restoring is to be postulated. We may say the “irritability” of an elastic ball is re-established by its elasticity. A certain analogy to this case may perhaps be found in the muscle. But the irritability of nerves with respect to nervous conduction, and of glands with respect to secretion, or of the articulations ofMimosamay be well understood, hypothetically at least, if we assume that the ordinary course of metabolic events is apt in itself to lead to a certain state or condition of the organs in question upon which their irritability is based. Certain general conditions of functioning, as for instance the presence of oxygen for the contraction of the muscle, would better be looked upon as necessary “means” of functioning than as being part of irritability as such. “Fatigue,” of course, may also be due to the absence of such “means” or to abnormal conditions originated by functioning itself.

93Rubner,Die Gesetze des Energieverbrauches bei der Ernährung, Leipzig u. Wein, 1902.

94The phenomenon of fever we leave out of account here; it is regarded by some as regulation, by others as a disturbance of heat regulation. Of course, if the first view should ever prove to be the right one, fever might be classified among the real regulations of the secondary type.

95Jahrb. wiss. Bot.36, 1901.

96Carbohydrates cannot be ionised, and therefore there is no doubt that in von Mayenburg’s experiments the organism itself is actively at work. As to compounds liable to ionisation, it has been noticed by Maillard that a certain regulatory character is contained simply in the physical fact that the degree of ionisation changes with concentration: decrease of concentration for instance would be followed by an increase of ionisation, and so the osmotic pressure may be preserved (C. rend. Soc. Biol.53, 1901, p. 880).

97In the different experiments of Nathansohn (Jahrb. wiss. Bot.38, 1902, and 39, 1903) the salinity of the medium was changed in such a way that there was in each case either an abnormal increase or an abnormal decrease in the concentration of one single ion necessary for metabolism. The cell was found to stand these abnormal changes in such a way that in the case of the increase of the concentration of the medium it did not allow more than a certain amount of the ion in question to come in, and that in the case of the decrease it did not allow more than a certain quantity of the ion to go out. It thus seems as if the permeability of the surface were adjusted to a certain minimum and to a certain maximum of every single ion or salt, the permeability being stopped from within to without, whenever the minimum, and from without to within, whenever the maximum is reached in the cell sap; both irrespective of proper physical osmotic equilibrium (“Physiologisches Gleichgewicht”). Thus, in fact, there only would be a case of primary regulation, nothing more. It would all appear rather similar to what occurs in the kidney. Of course we do not assert that our explanation is right, but it is possible and is at the same time the most simple, and it is our general practice always to prefer the most simple hypotheses.

98Many fishes are able to withstand great changes in the osmotic pressure of sea-water; the osmotic pressure of their body fluids, though never in a real physical equilibrium with the pressure of the medium, nevertheless may vary whenever the abnormal conditions of the latter exceed certain limits.

99See Stahl,Naturw. Wochenschrift, N. F. 5, 1906, No. 19.

100Arch. Anat. Phys., Phys. Abt. Suppl., 1902.

101The adaptive phenomena discovered by Gaidukow depend upon a real alteration in the formation of pigments. In the (primary) chromatic adaptation of pupae of Lepidoptera with respect to the colour of the ground they live upon, we only have the variable effects of pre-established chromatophores (Poulton,Phil. Trans. London, 178 B, 1888; Merrifield,Trans. Ent. Soc. London, 1898). The same holds for chromatic adaptations in crabs (Gamble and Keeble,Quart. Journ. Micr. Sci.43, 1900; Minkiewicz,Arch. Zool. exp. et gén.sér. 4, 7, notes, 1907).

102The theory of oxidation we have shortly sketched here was developed in chapter B. 5, of myOrganische Regulationen. Recent discoveries of Winterstein’s (Zeitschr. allg. Physiol.6, 1907) have given the strongest support to my hypothetic statements, and, in fact, can be said to have brought the doctrine of organic oxidation to a critical point. There can be no doubt that oxygen not only plays the “antipoisonous” rôle I had assigned to it, but that it is not even of such great importance for the supply of functional energy as former times had assumed. No doubt it serves to drive the functional machine, but decomposition of certain chemical constituents of the organism serves this purpose even more. The latter does so in the most fundamental and original manner, so to speak, whilst oxidation only burns up its products. Almost all elemental functions, in nerve-tissue at least, go on very well in the absence of oxygen, provided that certain “poisonous” substances, resulting from this anaërobic metabolism, are constantly removed. In normal conditions that is done by oxygen, and in doing so oxygen certainly assists the supply of energy, but it does not furnish the whole of it. The difference between so-called “aërobic” and “anaërobic” life almost completely disappears under such a view, and many so-called “regulations,” of course, disappear at the same time; there is no more “intramolecular respiration.”

103But nevertheless albumen is not to be replaced altogether in vertebrates by fat or carbohydrate; it probably serves some special function besides combustion, even in the adult.

104Arch. Entw. Mech.18, 1904.

105To a physiological friend of mine I owe the suggestion that it is the permanently functioning tissues which stand hunger better than the others, at least if the sexual cells might be regarded as capable of asécrétion internein all cases. Then the adaptations in the state of hunger might be said to be reduced in some degree to “functional adaptation.” But it must remain an open question, it seems to me, whether such a view may indeed hold in the face of the facts observed inPlanariaand infusorians.

106In all cases where fungi of the same species are able to live on different hosts, that is, to penetrate membranes of a different chemical character, a similar objection as to the “secondary” type of such a regulation may be made.

107The discovery of Weinland that adult dogs are able to produce “lactase” in their pancreas, whenever they are fed, quite abnormally, with milk-sugar, has recently been said to be vitiated by an analytical mistake.

108Compare the excellent review of the subject by Bayliss and Starling in theErgebnisse der Physiologie, 5, 1906, p. 664. The reader who misses here an analysis of the brilliant discoveries of Pawlow and his followers, relating to so-called “psychical and associative secretion,” will find these facts dealt with in another section of the book. These facts, indeed, would prove vitalism, it seems to me.

109It would be a true secondary metabolic regulation, if after the extirpation of one gland another different one were to assume its function. Nothing is known in this respect except a few rather doubtful observations about the interchange of functions between thymus and thyroid, except also the fact that the so-called lymph-glands increase in size after the extirpation of the spleen. Even here, of course, a sort of “restitution” would be included in adaptation proper.

110A good review is given by E. Fromm,Die chemischen Schutzmittel des Tierkörpers bei Vergiftungen, Strassburg, 1903.

111Davenport,Arch. Entw. Mech.2, 1895–1896, and Hausmann,Pflüger’s Arch.113, 1906.

112Leçons sur la pathologie comparée de l’inflammation, Paris, 1902.

113The other steps or phases in the process of inflammation have also been regarded as adaptive: the increased quantity of body fluid for instance is said to serve to dilute poisonous substances.

114See Jacoby,Immunität und Disposition, Wiesbaden, 1906.

115Collected Studies on Immunity by Ehrlich and his Collaborators, translated by Ch. Bolduan, New York and London, 1906.

116So-called genuine or innate immunity, in contrast to the immunity which is acquired, is of course a case of adaptedness only and not of adaptation. There also exists a high degree of specific adaptedness in some animals with regard to their faculty of coagulating blood. (See Leo Loeb,Biol. Bull.9, 1905.)

117We cannot do more than barely mention here the problem of the localisation of anti-body production. In general it seems to be true that anti-bodies are produced by those cells which require to be protected against toxins; that would agree with the general rule, that all compensation of the change of any functional state proceeds from the part changed in its function.

118Here again I should like to except from this statement the discoveries of Pawlow. See page204, note108.

119The few cases of an “improvement” of morphogenetic acts in hydroids described by myself are too isolated at present to be more than mere problems (Arch. Entw. Mech.5, 1897). The same is true, it seems to me, with regard to certain recent discoveries made by R. Pearl onCeratophyllum(Carnegie Inst. Wash. Publ.No. 58, 1907); and by Zeleny on a medusa (Journ. exp. Zool.5, 1907). Pawlow’s discovery, that the enzymotic composition of the pancreatic fluid in dogs becomes more and more adapted to a specific composition of the food (either meat or bread and milk) the longer such a specific composition is offered to the individual animal, may probably be understood as a case of mere functional adaptation of the cells of the digestive glands, if it stands criticism at all (see Bayliss and Starling,Ergeb. Physiol.5, 1906, p. 682).

120Experiments carried out in the “Biologische Versuchsanstalt” at Vienna indeed have shown that many animal types are capable of at least a certain degree of restitution, although they had previously been denied this faculty by zoologists.

121Ueber das Gedächtnis als eine allgemeine Function der organischen Materie, Wien, 1870. New edition inKlassiker d. exakt. Wiss., Leipzig, Engelmann.

122Die Mneme, Leipzig, 1904.

123Driesch,Organ. Regul.1901.

124The “ideal whole” is also proved to exist, if anygiven“Anlage,” say of a branch, is forced to give origin to a root, as has really been observed in certain plants. This case, like many other less extreme cases of what might be called “compensatory heterotypy,” are best to be understood by the aid of the concept of “prospective potency.” It is very misleading to speak of a metamorphosis here. I fully agree with Krašan about this question. See also page112, note48, and myOrgan. Regul.pp. 77, 78.

125Winkler has discovered the important fact, that the adventitious buds formed upon leaves may originate either from one single cell of the epidermis or from several cells together; a result that is very important with respect to the problem of the distribution of “potencies.”

126The “regeneration” of the brain of annelids for instance is far better regarded as an adventitious formation than as regeneration proper: nothing indeed goes on here at the locality of the wound; a new brain is formed out of the ectoderm at a certain distance from it.

127A full “analytical theory of regeneration” has been developed elsewhere (Organ. Regul.p. 44, etc.). I can only mention here that many different problems have to be studied by such a theory. The formation of the “Anlage” out of the body and the differentiation of it into the completely formed results of regeneration are two of them. The former embraces the question about the potencies not only of the regenerating body but of the elements of the Anlage also; the latter has to deal with the specific order of the single acts of regenerative processes.

128And, of course, at the root of every new starting of certain parts of morphogenesis also, as in regeneration and in adventitious budding; these processes, as we know, being also founded upon “complex-equipotential systems,” which have had their “genesis.”

129New edition in the “Klassiker d. exakt. Wiss.” Leipzig, Engelmann; see also Bateson,Mendel’s Principles of Heredity, Cambridge, 1902.

130For the sake of simplicity I shall not deal here with those cases of hybridisation in which one quality is “recessive,” the other “dominant,” but only allude to the cases, less numerous though they be, where a real mixture of maternal and paternal qualities occurs.

131This hypothesis was first suggested by Sutton and is at present held by orthodox Mendelians; but probably things are a little more complicated in reality, as seems to be shown by some facts in the behaviour of so-called “extracted recessives.” In Morgan’sExperimental Zoology, New York, 1907, a full account of the whole matter is given.

132Arch. Entw. Mech.21, 22, and 24, 1906–7; see also Doncaster,Phil. Trans. Royal Soc.London, B. 196, 1903. The influence of different temperature upon the organisation of the hybrids is not always quite pure, inasmuch as the paternal and the maternal forms may themselves be changed by this agent. In spite of that there exists an influence of the temperature upon the hybridas such, at least with regard to certain features of its organisation.

133Only the nucleus of the egg had entered its first stages of activity.

134The first proof of vitalism, indeed, rests upon the analysis of the differentiation of an harmonious-equipotential system as awhole: thiswholecannot be a machine that would relate to differentiation as awhole; the question whether there might be any machines distributedinthe whole, in the form of the nuclei is of no importance at all in this argument. Moreover the pressure experiments (see page63) prove the unimportance of such “machines” for the specificity of differentiation, and the second proof of vitalism shows that the nuclei cannot be regarded as machines accounting for differentiation inanyway.

135Boveri tried to fertilise enucleated fragments of the egg ofSphaerechinuswith the sperm ofEchinus. He failed to get any results in isolated experiments, but found a few small larvae of the pureEchinustype in large cultures consisting of shaken eggs. But later experiments on hybridisation in sea-urchins have shown that a full hybrid ofEchinusandSphaerechinusmay be purely paternal also.

136Surely the new results of Herbst, mentioned above, are another indication of the importance of something in the nucleus. The first stage in parthenogenesis, which he used in his experiments, is a nuclear phenomenon.

137Boveri (Ergebn. üb. d. Konstitution etc. des Zellkerns, Jena, 1904; and “Zellen-Studien VI.”Jen. Zeitschr.43, 1907) has made it highly probable by experiments that the different chromosomes of the nucleus of the sexual products play a different part in morphogenesis, though not in the sense of different single representatives of different single organs. This doctrine, of course, would not alter the whole problem very much: the chromosomes would only bemeansof morphogenesis and nothing else, no matter whether they were of equal or of different formative value. It only is with regard to the problem of the determination of sex (see page107, note46), that the morphogenetic singularity ofonecertain specific chromosome can be said to be proved.

138H. M. Vernon,Variations in Animals and Plants, London, 1903.

139De Vries,Die Mutationstheorie, i., 1901; and Klebs,Jahrb. wiss. Bot.42, 1905.

140They would not be “real exceptions” if Klebs (Arch. Entw. Mech.24, 1907) were right in saying that both variations and mutations owe their existence to external agents. What is reallyprovedby Klebs is the possibility of changing thetypeof a curve of variation and of provoking certain discontinuous varieties by external means. See also Blaringhem (Comptes rend.1905–6, andSoc. de Biol.59, 1905), and MacDougal (Rep. Depart. Bot. Res., 5th Year-book Carnegie Inst., Washington, 129).

141H. de Vries,Species and Varieties: their Origin by Mutation, London, 1905. A short review of the “mutation-theory” is given by Francé inZeitschrift f. d. Ausbau d. Entwickelungslehre, i. 1907. It is well known that Gautier, and, in the first place, Korshinsky, advocated a similar view previous to the authors named in the text.

142Recent years have created the beginnings of a systematics based on chemical differences of metabolism and its products: such differences in fact have been found to go hand in hand with diversities of the type in some cases (v. Bunge, Przibram, etc.).

143We prefer this unpretending definition of the theory of descent to every other. As soon as one introduces into the definition the concept of the “transmutability of species,” the term “species” would require a special definition, and that would lead to difficulties which it is unnecessary to deal with for our main purposes. It has been remarked by Krašan, (Ausichten und Gespräche über die individuelle und specifische Gestaltung in der Natur) and by several other writers, that the problem of mutability or immutability of course relates to the individuals in the first place. I should like to add to this remark that the possibility must be admitted of the individuals being transmutable, whilst the “species” are not transmutable at the same time, the line of the “species” being a fixed order, through which the “individuals” have to pass in the course of their generations. What is meant here will become clearer, when we study the different possible aspects of “phylogeny.”

144It seems to me that my argument gives a broader logical basis to the theory of descent than does that of G. Wolff (Die Begründung der Abstammungslehre, München, 1907). Wolff starts from the concept of organic teleology, and thus finds the only reason for accepting the theory of transformism in the existence of so-called “rudimentary organs”; these organs would form an obstacle to teleology if they could not be regarded as inherited.

145See Wigand,Der Darwinismus und die Naturforschung Newton’s und Cuvier’s, Braunschweig, 1874–7; Nägeli,Mechanisch-physiologische Theorie der Abstammungslehre, München, 1884; G. Wolff,Beiträge zur Kritik der Darwin’schen Lehre, 2nd ed. Leipzig, 1898; etc.

146Darwinismus und Lamarckismus, München, 1905.

147This would not be true, if the varieties of plants produced by Blaringhem, Klebs, and MacDougal by means ofexternalagents were really “mutations” (comp. page 238, note 3).

148Of course, the inheritance of mutations would imply a certain sort of “inheritance of acquired characters,” on the condition stated in the preceding note. But, probably, the germs of the next generation might be regarded here as being directly affected by the external agent, in a manner that will briefly be mentioned later on in the text.

149Comp. page 238, note 2.

150Certain English authors have applied the term “modification” to all kinds of organic properties acquired from without, whether they are adapted or not.

151Of course the inheritance of specific values from the results of fluctuating variations, leading to new averages of variability (see p.265), may also be understood in this manner, the conditions of nourishment acting upon the adult and upon its germs equally well.

152Berichte üb. d. Sitzung. d. Ges. f. Bot., Hamburg, 1887, 3 Heft.

153Quite recently Kammerer (Arch. Entw. Mech.25, 1907, p. 7) has published very important experiments on the inheritance of “acquired” modifications with regard to the peculiarities of reproduction inSalamandra atraandS. maculosa. It seems rather improbable—though not absolutely impossible—that the germ cells were directly affected by the external modifying agent in this case.

154We have not spoken about the hypothetic inheritance of pure physiological adaptations, for it is clear without further discussion that innate specific immunity, for instance, being a specific “adaptedness” (seep.186)mightbe due to the inheritance of the results of active immunity as an adaptation, just as adaptive congenital structuresmightbe due to such an inheritance.

155C. E. v. Baer clearly discriminated between the type, the degree of organisation, and the histological structure. All these three topics indeed have to be taken into account separately; the third alone is of the adaptive type. All of them may be independent of each other: the Amoeba may be as adapted histologically as is a high vertebrate, but it is of much lower type; and in its own type it is of a lower degree of organisation than Radiolaria are.

156I repeat once more that we are dealing here with dogmatic “Neo-”Lamarckism exclusively. This theory indeed claims to explainallfeatures and properties of organic bodies on the basis of the feeling of needs and storing of contingent fulfilments and on this basis alone, just as dogmatic “Neo”-Darwinism claims to account forallthose phenomena on the ground of contingent variations and natural selection. Darwin himself, as we have seen, intentionally left unexplained certain primary features of life and therefore cannot be blamed for having failed to explain them, though even then his theory remains wrong. Lamarck personally considered a real primary organisatory law of phylogeny as being of fundamental importance, and therefore he is not in the least responsible if “Neo-Lamarckism” fails as a universal theory.

157Compare also the excellent criticism of Lamarckism lately given by G. Wolff,Die Begründung der Abstammungslehre, München, 1907.

158It has also very often been said by Darwinians that Lamarckism is only able to explain those cases of adaptedness which relate to active functioning but not mere passive adapted characters, like “mimicry” for example. But this argumenttaken by itself, it seems to me, would not be fatal to Neo-Lamarckism in the special form August Pauly gave to this doctrine.

159But nothing more. All “mutations” hitherto observed in nature or (comp. page 238, note 3) experimentally produced relate only to “varieties” and not to “species.” One could hardly say that the recent investigations about the production of mutations byexternalmeans have strengthened their importance for the general theory of transformism.

160The word “possible” relating to originating, of course, not to surviving. It is here that natural selection may acquire its logical importance alluded to above (see page264).

161The discussions in the second volume of this book will show the possible significance of such an analysis. We at present are dealing with entelechy in a quasi-popular manner.

162See pp.26,45,54, etc.

163An immanent vitalistic phylogenywithouta pre-established end has recently been advocated by H. Bergson (L’évolution créatrice, Paris, 1907).

164In this connection the problem may be raised, whether there can be such a thing as unchangeable “species” in spite of the mutability of the individuals. Compare page 251, note 1.

165On account of the limited size of the earth a certain final stage of human civilisation might be expected in a future time; but it would be the size of the earth which determined this end, and not the process of civilisation itself.

166Die Grenzen der naturwissenschaftlichen Begriffsbildung, Tübingen and Leipzig, 1902.

167The word “universality” to be understood here in quite an unpretentious quasi-popular meaning, not strictly epistemologically.

168To avoid mistakes I wish to say here most emphatically that, according to Rickert, the method of history is regarded as completelyfreefrom subjectivity as soon as its “values” are onceestablished. But this cannot avail to save the theory.

169This is a rather optimistic conception of “history.” Personally, I must confess that even its emotional and practical importance seems to me to be at least diminished by the retarding effects which all sorts of “historical” considerations—in science as well as in arts and in public life—carry with them. All real progress is non-historical—and its champions almost always have become martyrs: this fact seems not to recommend history as a means of education, except for persons of a very strong character.

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