FOOTNOTES

Fig. 11.—Acarus equi. A degenerate Spider or mite parasitic on the skin of the horse.

Fig. 12.—Degenerate Spider (Demodex foliculorum) found in the skin of the human face.

The instances of degeneration which we have so far examined are due to parasitism, except in the example of the Barnacle, where we have an instance of degeneration due to sessile and immobilehabit of life. We may now proceed to look at some sessile or immobile animals which are not usually regarded as degenerate, but which, I think, there is every reason to believe are the degenerate descendants of very much higher and more elaborate ancestors. These are certain marine animals, the Ascidians, or sea-squirts. These animals are found encrusting rocks, stones, and weeds on the sea bottom. Sometimes they are solitary (Fig. 13), but many of them produce buds, like plants, and so form compound masses or sheets of individuals all connected and continuous with one another, like the buds on a creeping plant (Fig. 14).

Fig. 13.—Two adult Ascidians: to the left Phallusia—to the right Cynthia: the incurrent and excurrent orifices are seen as two prominences. Half the natural size.

We will examine one of the simple forms—a tough mass like a leather bottle with two openings; water is continually passing in at the one and out atthe other of these apertures. If we remove the leathery outer-case (Fig. 15), we find that there is a soft creature within which has the following parts:—Leading from the mouth a great throat, followed by an intestine. The throat is perforated by innumerable slits, through which the water passes into a chamber—the cloaca: in passing, the water aërates the blood which circulates in the framework of the slits. The intestine takes a sharp bend, which causes it to open also into the cloaca. Between the orifice of the mouth and of the cloaca there is a nerve-ganglion.

Fig. 14.—A colony of compound Ascidians (Botryllus) growing on a piece of sea-weed (Fucus). Each star corresponds to eight or more conjoined Ascidians. Natural size.

My object in the next place is to show that the structure and life-history of these Ascidians may be best explained on the hypothesis that they are instances of degeneration; that they are the modified descendants of animals of higher, that is more elaborate structure, and in fact are degenerate Vertebrata, standing in the same relation to fishes, frogs, and men, as do the barnacles to shrimps, crabs, and lobsters.

Fig. 15.—Anatomy of an Ascidian (Phallusia). At the top is the mouth, to the right the orifice of the cloaca. In the cloaca lies an egg, and above it the oblong nerve ganglion. The perforated pharynx follows the mouth and leads to the bent intestine which is seen to open into the cloaca. The space around the curved intestine is the body-cavity; in it are seen oval bodies, the eggs, and quite at the lower end the curved heart. The root-like processes at the base serve to fix the Ascidian to stones, shells, or weed.

The young of some, but by no means of all theseAscidians, have a form totally different from that of their parents. The egg of Phallusia gives rise to a tadpole, a drawing of which placed side by side with the somewhat larger tadpole of the common frog is seen in the adjoining figure (Fig. 16). The young Ascidian has the same general shape as the young frog, but not only this; the resemblance extends into details, the internal organs agreeing closely in the two cases. Further still as shown by the beautiful researches of the Russian naturalist, Kowalewsky, the resemblance reaches absolute identity when we examine the way in which the various organs arise from the primitive egg-cell. Tail, body, spiracle, eye, and mouth, agree in the two tadpoles, the only important difference being in the position of the two mouths and in the fact that the Ascidian has one eye while the frog has two.

Fig. 16.—Tadpole of Frog and of Ascidian. Surface view.

Fig. 17.—Tadpole of Frog and of Ascidian. Diagrams representing the chief internal organs.

Now let us look at the internal organs (Fig. 17). There are four structures, which areall fourpossessed at some time of their lives by all those animals which we call the Vertebrata, the great branch of the pedigree to which fishes, reptiles, birds, beasts, and men belong. And the combination of these marks or structural peculiarities is an overwhelming piece of evidence in favour of the supposition that the creatures which possess this combination are derived from one common ancestor. Just as one would conclude that a man whom one might meet, say on Salisbury Plain,mustbelong to the New Zealand race, if it were found not only that he had the colour, and the hair, and the shape of head of a New Zealander, but also that hewas tattooed like a New Zealander, carried the weapons of a New Zealander, and, over and above in addition to these proofs, that he talked the Maori language and none other; so here, in the case of the vertebrate race, there are certain qualities and possessions, the accumulation of which cannot be conceived of as occurring in any animal but one belonging to that race. These four great structural features are—first, the primitive backbone or notochord; second, the throat perforated by gill-slits; third, the tubular nerve-centre or spinal cord and brain placed along the back; and lastly, and perhaps most distinctive and clinching as an evidence of affinity, the myelonic or cerebral eye.

Now let us convince ourselves that these four features exist not only in the frog’s tadpole, as they do in all fishes, reptiles, birds, and beasts, but that they also exist in the Ascidian tadpole, and, it may be added, co-exist in no other animals at all.

The corresponding parts are named in Figs. 16 and 17, in such a way as to render their agreement tolerably clear, whilst in Fig. 18 a more detailed representation of the head of an Ascidian tadpole is given.

Fig. 18.—Ascidian Tadpole with a part only of the tailC.N, nervous system with the enlarged brain in front and the narrow spinal cord behindn;N´, is placed in the cavity of the brain:O, the single cerebral eye lying in the brain;a, similarly placed auditory organ;K, pharynx;d, intestine;o, rudiment of the mouth;ch, notochord or primitive backbone. (From Gegenbaur’s “Elements of Comparative Anatomy.”)

It is clear then that the Ascidians must be admitted to be Vertebrates, and must be classified in that great sub-kingdom or branch of the animal pedigree. The Ascidian tadpole is very unlike its parent the Ascidian, and has to go through a process ofdegenerationin order to arrive at the adult structure. The diagrams which are reproduced in Figs. 19 and 20, show how this degeneration proceeds. It will be observed, that in somewhat the same manner as the young barnacle, the young Ascidian fixes itself to a stone by its head: then the tail with its notochord and nerve-chord atrophies. The body grows and gradually changes its shape, whilst the cloacal chamber forms. The brain remains quite small and undeveloped, and the remarkable myelonic eye (the eye inthe brain) disappears. The number of gill-slits increases as the animal grows in size and its outer skin becomes tough and leather-like.

Fig. 19.—Degeneration of Ascidian Tadpole to form the adult. The black pieces represent the rock or stone to which the Tadpole has fixed its head.

Fig. 20.—Very young Ascidian with only two gill-slits. Compare with Fig 15; which is, however, seen from the other side, so that left there corresponds to right here.

Fig. 21.—Section through the eye (“surface-eye”) of a Water-beetle’s larva. All the cells are seen to be in a row continuous withh, the cells of the outermost skin or ectoderm.p, pigmented cells;r, retinal cells connected atowith the optic nerve;g, transparent cells (forming a kind of “vitreous body”);l, cuticular lens. (From Gegenbaur’s “Elements of Comparative Anatomy,” after Grenacher.)

Before saying anything further on the subject of degeneration, it seems desirable once more to direct attention to the myelonic or cerebral eye which the Ascidian tadpole possesses in common with all Vertebrates. All other animals which have eyes develop the retina or sensitive part of the eye from theirouter skin(See Figs. 21 and 22, and explanation.) It is easy to understand that an organ which is to be affected by the light should form on thesurfaceof the body where the light falls. It has long been known as a very puzzling and unaccountable peculiarity of Vertebrates, that the retina or sensitive part of the eye grows out in the embryo as a bud or vesicle of the brain, and thus formsdeeplybelow the surface andaway fromthe light(see Fig. 23, and explanation). The Ascidian tadpole helps us to understand this, for it is perfectly transparent and has its eye actuallyinsideits brain. The light passes through the transparent tissues and acts on the pigmented eye, lying deep in the brain. We are thus led to the conclusion—and I believe this inference to be now for the first time put into so many words—that the original Vertebrate must have been a transparent animal, and had an eye or pair of eyesinsideits brain, like that of the Ascidian tadpole. As the tissues of this ancestral Vertebrate grew denser and more opaque, the eye-bearing part of the brain was forced by natural selection to grow outwards towards the surface, in order that it might still be in a position to receive the influence of the sun’s rays. Thus the very peculiar mode of development of the Vertebrate eye from two parts, a brain-vesicle (Fig. 23,A a, andB p r), and a skin-vesicle (Fig. 23,B e, l), is accounted for.

Fig. 22.—Section through the eye (“surface-eye”) of a Marine Worm (Neophanta).i, integument spreading over the front of the eyec;l, cuticular lens;h, cavity occupied by vitreous body;p, retinal cells;b, pigment;o, optic nerve:o´, expansion of optic nerve.

Fig. 23.—A.Vertical section through the head of a very young fish, showing in the centre the cavity of the brainc. On each side is a hollow outgrowth (a) which will form the retina of the fish’s eye (“cerebral eye”);b, will become the optic nerve connecting the brain and the retina;d, integument.—B.Later condition of the hollow outgrowth (a) ofA. Its outer wallris pressed against its deeper wallpby an ingrowth (l) from the outer skin (ectoderm)e;r, gives rise to the retinal cells, whilst onlyl, the cellular lens, is derived from the surface of the skin.

The cases of degeneration which I have up to this point brought forward, are cases which admit of very little dispute or doubt. They are attested by either the history of the individual development of the organisms in question, as in Sacculina, in the Barnacle, and in the Ascidian, or they are caseswhere the comparison of the degenerate animal, with others like it in structure, but not degenerate, renders the hypothesis of degeneration an unassailable one. Such cases are the Acarus or mite, and the skin-worm (Demodex).

We have seen that degeneration, or the simplification of the general structure of an animal, may be due to the ancestors of that animal having taken to one of two new habits of life, either the parasitic or the immobile. Other new habits of life appear also to be such as to lead to degeneration. Let us suppose a race of animals fitted and accustomed to catch their food, and having a variety of organs to help them in this chase—suppose such animals suddenly to acquire the power of feeding on the carbonic acid dissolved in the water around them just as green plants do. This would lead to a degeneration; they would cease to hunt their food, and would bask in the sunlight, taking food in by the whole surface, as plants do by their leaves. Certain small flat worms, by name Convoluta, of a bright green colour, appear to be in this condition. Their green colour is known to be the same substance as leaf-green; and Mr. Patrick Geddes has recently shownthat by the aid of this green substance they feed on carbonic acid, making starch from it as plants do. As a consequence we find that their stomachs and intestines as well as their locomotive organs become simplified, since they are but little wanted. These vegetating animals, as Mr. Geddes calls them, are the exact complement of the carnivorous plants, and show how a degeneration of animal forms may be caused byvegetative nutrition.

Another possible cause of degeneration appears to be the indirect one of minute size. It cannot be doubted that natural selection has frequently acted on a race of animals so as to reduce the size of the individuals. The smallness of size has been favourable to their survival in the struggle for existence, and in some cases they have been reduced to even microscopic proportions. But this reduction of size has, when carried to an extreme, resulted in the loss or suppression of some of the most important organs of the body. The needs of a very minute creature are limited as compared with those of a large one, and thus we may find heart and blood-vessels, gills and kidneys, besides legs and muscles, lost by the diminutive degenerate descendants of a larger race.That this is a possible course of change all will, I think, admit. It is actually exemplified in Appendicularia—the only adult representative of the Ascidian tadpole—still tadpole-like in form and structure, but curiously degenerate and simplified in its internal organs. This kind of degeneration is also exemplified in the Rotifers, or wheel animalcules, in the minute Crustacean water-fleas (Ostracoda), and in the Moss-polyps, or Polyzoa. Roughly then we may sum up the immediate antecedents of degenerative evolution as, 1, Parasitism; 2, Fixity or immobility; 3, Vegetative nutrition; 4, Excessive reduction of size. This is not a logical enumeration, for each of these causes involves, or may be inseparably connected with, one or more of the others. It will serve for the present as well as a more exhaustive analysis. (See Note C.)

And now we have to note an important fact with regard to theevidencewhich we can obtain of the occurrence of this process of degeneration. We have seen that the most conclusive evidence is that of the recapitulative development of the individual. The Ascidian Phallusia shows itself to be a degenerate Vertebrate by beginning life as atadpole. But such recapitulative development is by no means the rule. Quite arbitrarily, we find, it is exhibited in one animal and not in a nearly allied kind. Thus very many animals belonging to the Ascidian group have no tadpole young—just as some tree-frogs have no tadpoles. It is quite possible, and often, more often than not, occurs, thatthe most important partof the recapitulative phases are absent from the developmental history of an animal. The egg proceeds very rapidly to produce the adult form, and all the wonderful series of changes showing the animal’s ancestry are absolutely and completely omitted; that is to say, all those stages which are of importance for our present purpose. Just as certain bodies pass from the solid to the liquid state at a bound, omitting all intermediate phases of consistence, but giving evidence of “internal work” by the suggestive phenomenon of latent heat—so do these embryos skip long tracts in the historically continuous phases of form, and present to us only the intangible correlative “internal work” in place of the tangible series of embryonic changes of shape.

Now I want to put this case—a supposition—beforethe reader who has so far followed me in these pages. Suppose, as might well have happened, that the Barnacles, one and all, instead of recapitulating in their early life, were to developdirectly from the egg to the adult form, as so many animals do; should we have ever made out that they were degenerate Crustaceans? Possibly we should: their adult structure still bears important marks of affinities with crabs and shrimps; but as a matter of fact before their recapitulative development had been discovered they were classed by the great Cuvier and other naturalists with the Molluscs, the mussels and snails.

Suppose again thatallthe existing Ascidians, as many of them actually have, had long ago lost their recapitulative history in growth from the egg: suppose that no such a thing as an Ascidian tadpole existed, but that the Ascidian’s egg grew as directly as possible into an Ascidian, in every living species of the group. This might easily be the case. Then most assuredly we should not have the least notion that the Ascidians were degenerate Vertebrates. We should still class them where they used to be classed before the Russian naturalist Kowalewsky discovered the true history and structure of the Ascidian tadpole.I believe that I shall have the assent of every naturalist when I say that the vertebrate character of the Ascidians and the history of their degeneration would never have been suspected, or even dreamed of, had the Ascidian tadpoles ceased to appear in the course of the Ascidian development at a geological period anterior to the present epoch.

This being the case, it must be admitted that it is quitepossible—I do not say more than possible—that other groups of animals besides parasites, Barnacles, and Ascidians, are degenerate. It is quite possible that animals with considerable complexity of structure, at least as complex as the Ascidians, may have been produced by degeneration from still more highly-organized ancestors. Any group of animals to which we can turn may possibly be the result of degeneration, and yet offer no evidence of that degeneration in its growth from the egg.

Accordingly, wherever we can note that a group of organisms is characterized by habits likely to lead to degeneration, such as I have enumerated, viz., parasitism or immobility, or certain special modes of nutrition, or again, by minute size of its representatives—there we are justified in applying thehypothesis of degeneration, even in the absence of any confirmatory evidence from embryology. When we so apply this hypothesis we find in not a few cases, in working over the details of the organization of many different animals by the light which it affords—that much becomes clear and assignable to cause which, on the hypothesis either of “balance” or of “elaboration,” is quite hopelessly obscure. As examples of groups of animals which can thus be satisfactorily explained I may cite first of all the Sponges: as only somewhat less degenerate, we have all the Polyps and Coral-animals, also the Starfishes. Amongst the Mollusca—the group of headless bivalves, the oysters, mussels and clams, known as the Lamellibranchs, are, when one once looks at their structure in this light, clearly enough explained as degenerated from a higher type of head-bearing active creatures like the Cuttle-fish; whilst the Polyzoa or Moss-polyps stand in precisely the same kind of relation to the higher Mollusca as do the Ascidians to the higher Vertebrates: they have greatly degenerated, and become minute encrusting organisms which, like some of the Ascidians, build up colonies by plant-like budding growth. The Rotifers, or wheel animalcules,I have already mentioned as best explained by the supposition that they are the descendants of far larger and more fully-organized animals provided with locomotive appendages or limbs: they have dwindled and degenerated to their present minute size and curiously suggestive structure.

Besides these there are other very numerous cases of animal structure which can best be explained by the hypothesis of degeneration. A discussion of these, and a due exposition of the application of the hypothesis of degeneration to the various groups just cited, would involve a complete treatise on comparative anatomy and embryology, and lead far beyond the limitations of this little volume.

All that has been, thus far, here said on the subject of Degeneration is so much zoological specialism, and may appear but a narrow restriction of the discussion to those who are not zoologists. Though we may establish the hypothesis most satisfactorily by the study of animal organization and development, it is abundantly clear that degenerative evolution is by no means limited in its application to the field of zoology. It clearly offers an explanation of many vegetable phenomena, and is already admitted bybotanists as the explanation of the curious facts connected with the reproductive process in the higher plants. As a further example of its application in this field, the yeast-plant may be adduced, which is in all probability a degenerate floating form derived from a species of mould (Mucor). In other fields, wherever in fact the great principle of evolution has been recognised, degeneration plays an important part. In tracing the development of languages, philologists have long made use of the hypothesis of degeneration. Under certain conditions, in the mouths and minds of this or that branch of a race, a highly elaborate language has sometimes degenerated and become no longer fit to express complex or subtle conceptions, but only such as are simpler and more obvious. (See Note D.)

The traditional history of mankind furnishes us with notable examples of degeneration. High states of civilisation have decayed and given place to low and degenerate states. At one time it was a favourite doctrine that the savage races of mankind were degenerate descendants of the higher and civilised races. This general and sweeping application of the doctrine of degeneration has been proved to be erroneous bycareful study of the habits, arts, and beliefs of savages; at the same time there is no doubt that many savage races as we at present see them are actually degenerate and are descended from ancestors possessed of a relatively elaborate civilisation. As such we may cite some of the Indians of Central America, the modern Egyptians, and even the heirs of the great oriental monarchies of præ-Christian times. Whilst the hypothesis of universal degeneration as an explanation of savage races has been justly discarded, it yet appears that degeneration has a very large share in the explanation of the condition of the most barbarous races, such as the Fuegians, the Bushmen, and even the Australians. They exhibit evidence of being descended from ancestors more cultivated than themselves.

With regard to ourselves, the white races of Europe, the possibility of degeneration seems to be worth some consideration. In accordance with a tacit assumption of universal progress—an unreasoning optimism—we are accustomed to regard ourselves as necessarily progressing, as necessarily having arrived at a higher and more elaborated condition than that which our ancestors reached, and as destinedto progress still further. On the other hand, it is well to remember that we are subject to the general laws of evolution, and are as likely to degenerate as to progress. As compared with the immediate forefathers of our civilisation—the ancient Greeks—we do not appear to have improved so far as our bodily structure is concerned, nor assuredly so far as some of our mental capacities are concerned. Our powers of perceiving and expressing beauty of form have certainlynotincreased since the days of the Parthenon and Aphrodite of Melos. In matters of the reason, in the development of intellect, we may seriously inquire how the case stands. Does the reason of the average man of civilised Europe stand out clearly as an evidence of progress when compared with that of the men of bygone ages? Are all the inventions and figments of human superstition and folly, the self-inflicted torturing of mind, the reiterated substitution of wrong for right, and of falsehood for truth, which disfigure our modern civilisation—are these evidences of progress? In such respects we have at least reason to fear that we may be degenerate. Possibly we are all drifting, tending to the condition of intellectual Barnacles or Ascidians. It is possiblefor us—just as the Ascidian throws away its tail and its eye and sinks into a quiescent state of inferiority—to reject the good gift of reason with which every child is born, and to degenerate into a contented life of material enjoyment accompanied by ignorance and superstition. The unprejudiced, all-questioning spirit of childhood may not inaptly be compared to the tadpole tail and eye of the young Ascidian: we have to fear lest the prejudices, pre-occupations, and dogmatism of modern civilisation should in any way lead to the atrophy and loss of the valuable mental qualities inherited by our young forms from primæval man.

There is only one means of estimating our position, only one means of so shaping our conduct that we may with certainty avoid degeneration and keep an onward course. We are as a race more fortunate than our ruined cousins—the degenerate Ascidians. For us it is possible to ascertain what will conduce to our higher development, what will favour our degeneration. To us has been given the power toknow the causes of things, and by the use of this power it is possible for us to control our destinies. It is for us by ceaseless and ever hopeful labourto try to gain a knowledge of man’s place in the order of nature. When we have gained this fully and minutely, we shall be able by the light of the past to guide ourselves in the future. In proportion as the whole of the past evolution of civilised man, of which we at present perceive the outlines, is assigned to its causes, we and our successors on the globe may expect to be able duly to estimate that which makes for, and that which makes against, the progress of the race. The full and earnest cultivation of Science—the Knowledge of Causes—is that to which we have to look for the protection of our race—even of this English branch of it—from relapse and degeneration.

FOOTNOTES[1]These pages formed a discourse delivered before the British Association at Sheffield on the evening of August 22nd, 1879, under the presidency of Professor Allman, LL.D., F.R.S.[2]See Note A.[3]See Note B.[4]Der Ursprung der Wirbelthiere und das Princip des Functionswechsels. Leipzig, 1875.

[1]These pages formed a discourse delivered before the British Association at Sheffield on the evening of August 22nd, 1879, under the presidency of Professor Allman, LL.D., F.R.S.

[2]See Note A.

[3]See Note B.

[4]Der Ursprung der Wirbelthiere und das Princip des Functionswechsels. Leipzig, 1875.

“Die Phantasie ist ein unentbehrliches Gut; denn sie ist es, durch welche neue Combinationen zur Veranlassung wichtiger Entdeckungen gemacht werden. Die Kraft der Unterscheidung des isolirenden Verstandes sowohl, als der erweiternden und zum allgemeinen strebenden Phantasie sind dem Naturforscher in einem harmonischen Wechselwirken nothwendig. Durch Störung dieses Gleichgewichts wird der Naturforscher von der Phantasie zu Träumereien hingerissen, während diese Gabe den talentvollen Naturforscher von hinreichender Verstandesstärke zu den wichtigsten Entdeckungen führt.”—Johannes Müller,Archiv für Anatomie, 1834.

To many persons the conclusion that man is the naturally modified descendant of ape-like ancestors appears to be destructive of the belief in an immortal soul, and in the teachings of Christianity; and accordingly they either reject Darwinism altogether, or claim for man a special exemption from the mode of origin admitted for other animals.

It seems worth while, in order to secure a calm and unprejudiced consideration for the teachings of Darwinism, to point out to such persons that, as a matter of fact, whatever views we may hold with regard to a soul and the Christian doctrines, they cannot be in the smallest degree affected by the admission that man has been derived from ape-like ancestors by a process of natural selection, so long as the demonstrable fact, not denied by any sane person, is admitted, namely, that every individual man grows by a process of natural modification from a homogeneous egg-cell or corpuscle. Assuredly it cannot lower our conception of man’s dignity if wehave to regard him as “the flower of all the ages,” bursting from the great stream of life which has flowed on through countless epochs with one increasing purpose, rather than as an isolated, miraculous being, put together abnormally from elemental clay, and cut off by such portentous origin from his fellow animals, and from that gracious Nature to whom he yearns with filial instinct, knowing her, in spite of fables, to be his dear mother.

A certain number of thoughtful persons admit the development of man’s body by natural processes from ape-like ancestry, but believe in the non-natural intervention of a Creator at a certaindefinitestage in that development, in order to introduce into the animal which was at that moment a man-like ape, something termed “a conscious soul,” in virtue of which he became an ape-like man. It appears to me perfectly legitimate and harmless for individuals to make such an assumption if their particular form of philosophy or of religion requires it. Such an assumption does not in any way traverse the inferences from facts to which Darwinism leads us; at the same time zoological science does not, and cannot be expected to, give any support to such an assumption. The gratuitous and harmless nature of the assumption so far as zoological science is concerned, and accordingly the baselessness of the hostility to Darwinism of those who choose to make it, may be seen by the consideration of a parallel series of factsand assumptions, which puts the matter clearly enough in its true light.

No one ventures to deny, at the present day, that every human being grows from the eggin utero, just as a dog or a monkey does; the facts are before us and can be scrutinised in detail. We may ask of those who refuse to admit the gradual and natural development of man’s consciousness in the ancestral series, passing from ape-like forms into indubitable man, “How do you propose to divide the series presented by every individual man in his growth from the egg? At what particular phase in the embryonic series is the soul with its potential consciousness implanted? Is it in the egg? in the fœtus of this month or of that? in the new-born infant? or at five years of age?” This, it is notorious, is a point upon which Churches have never been able to agree; and it is equally notorious that the unbroken series exists—that the egg becomes the fœtus, the fœtus the child, and the child the man. On the other hand we have the historical series—the series, the existence of which is inferred by Darwin and his adherents. This is a series leading from simple egg-like organisms to ape-like creatures, and from these to man. Will those who cannot answer our previous inquiries undertake to assert dogmatically in the present case at what point in the historical series there is a break or division? At what step are we to be asked to suppose that the order of nature was stopped, and a non-naturalsoul introduced? The philosopher or theologian of this or that school may arbitrarily draw an imaginary line here or there in either series, and the evolutionist will not raise a finger to stop him. As long as truth in the statement of fact, and logic in the inference from observed fact are respected, there need be no hostility between evolutionist and theologian. The theologian is content in the case of individual development from the egg to admit the facts of individual evolution, and to make assumptions which lie altogether outside the region of scientific inquiry. So, too, it would seem only reasonable that he should deal with the historical series, and frankly accept the natural evolution of man from lower animals, declaring dogmatically, if he so please, but not as an inference of the same order as are the inferences of science, that something called the soul arrived at any point in the series which he may think suitable. At the same time, it would appear to be sufficient, even for the purposes of the theologian, to hold that whatever the two above-mentioned series of living things contain or imply, they do so as the result of a natural and uniform process of development, that there has been one “miracle” once and for all time. It should not be a ground of offence to any school of thinkers, that Darwinism, whilst leaving them free scope, cannot be made actually contributory to the support of their particular tenets.

The difficulties which the theologian has to meetwhen he is called upon to give some account of the origin and nature of the soul, certainly cannot be said to have been increased by the establishment of the Darwinian theory. For from the earliest days of the Church, ingenious speculation has been lavished on the subject. As to the origin of the individual soul, Tertullian tells us as follows:—De Anima, ch. xix.—“Anima velut surculus quidam ex matrice Adami in propaginem deducta, et genitalibus semine foveis commodata. Pullulabit tam intellectu quam et sensu.”

Whilst St. Augustine says:—“Harum autem sententiarum quatuor de anima, utrum de propagine veniant, an in singulis quibusque nascentibus mox fiant, an in corpora nascentium jam alicubi existentes vel mittantur divinitus, vel sua sponte labantur,nullam temere affirmari oporteret: aut enim nondum ista quæstio a divinorum librorum catholicis tractatoribus, pro merito suæ obscuritatis et perplexitatis, evoluta atque illustrata est; aut si jam factum est, nondum in manus nostras hujuscemodi litteræ provenerunt.”

A very important form of degeneration, not touched on in the text, is that exhibited in the Mexican axolotl, where the larval form of a Salamander develops generative organs, and is arrested in its further progress to the adult parental form. It is not possible to class this with the other phenomena which I have enumerated as Degeneration, since there is no modification of an adult structure, but simple arrest, and retention of the larval structure in all its completeness. I should call the phenomenon exhibited by axolotl “arrest” or “super-larvation” rather than degeneration.

The result of super-larvation is in so far similar to that of those changes to which it is desirable to restrict the term “degeneration,” that it may be classed under “simplificative evolution” as opposed to “elaborative evolution.” That there is a very real difference between super-larvation and degeneration may best be seen by taking a case of each process and instituting a comparison. Axolotl proceedsregularly on its course of development from the egg, but instead of passing from the aquatic gilled condition to the terrestrial gill-less adult form of the Salamander, it remains arrested in the earlier condition, develops its reproductive organs, and propagates itself. There is no loss or atrophy in this case, but simply a dead stop in a progressive course. On the other hand, as we have seen, the Ascidian loses, by a process of atrophy and destruction, a powerful locomotive organ, a highly-developed eye, a relatively large nervous system. The former may be compared to a permanent childishness, the latter to the second childhood, which is really atrophy and decay. It is highly probable that super-larvation has taken place at various epochs and in various groups of the animal kingdom, just as it does in axolotl, and yet we cannot hope for evidence fitted to establish its occurrence in any one case, where it is no longer possible by exceptional conditions to recover (as in the case of axolotl, which can experimentally be made to advance to the Salamander phase by proper treatment), the discarded, more developed adult form. By super-larvation it would be possible for an embryonic form developed in relation to special embryonic conditions and not recapitulative of an ancestry, to become the adult form of the race, and thus to give to the subsequent evolution of that race a totally and otherwise improbable direction.

It seems also exceedingly probable that “super-larvation” does not occur only as in axolotl through premature maturation of the reproductive organs, but the phenomenonmaydevelop itself more slowly by a gradual creeping forward, as it were, of larval features. Just as the adaptations acquired in, and having relation to, later life tend to show themselves in an early period of the development of the individual and out of due season; so do characters acquired by the early embryo, and having relation only to this early period of life tend to remain as permanent structures, and by their invasion to perturb the adult organization. Such perturbation may tendeitherto simplification or elaboration.

The term (degeneration of language) includes two very distinct things; the one is degeneration of grammatical form, the other degeneration of the language as an instrument of thought. The former is a far commoner phenomenon than the latter, and, in fact, whilst actually degenerating so far as grammatical complexity is concerned, a language may be at the same time becoming more and more serviceable, or more and more perfect as an organ having a particular function. The decay of useless inflexions and the consequent simplification of language may be compared to the specialization of the one toe of the primitively five-toed foot of the horse, whilst the four others which existed in archaic horses are, one by one, atrophied. Taken by itself, this phenomenon may possibly be described as degeneration, but inasmuch as the whole horse is not degenerate but, on the contrary, specialized and elaborated, it is advisable to widely distinguish such local atrophy from general degeneration. In the same way languagecannot, in relation to this question, be treated as a thing by itself—it must be regarded as a possession of the human organism, and the simplification of its structure merely means in most cases its more complete adaptation to the requirements of the organism.

True degeneration of language is therefore only found as part and parcel of a more general degeneration of mental activity. To some extent the conclusion that this or that language, as compared with its earlier condition, exhibits evidence of such degeneration, must be matter of taste and open to discussion. For instance, the English of Johnson may be regarded as degenerate when compared with that of Shakspeare. There is less probability of a difference of opinion as to the degeneracy of modern Greek as compared with “classical” Greek; or of some of the modern languages of Hindustan as compared with Sanskrit, and I am informed that the same kind of degeneration is exhibited by modern Irish as compared with old Irish. Degeneration, in the proper sense of the word, so far as it applies to language, would seem to mean simply a decay or diversion of literary taste and of literary production in the race to which such language may be appropriate.

LONDON:R. CLAY, SONS, AND TAYLOR,BREAD STREET HILL, E.C.

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