The science of language, with its great results, displays the most important side of human nature-man in the elevation which he has gradually acquired above the rest of the living world-but it displays this side alone. Although the founders of linguistic inquiry, of whom we have already spoken, had already represented man as first acquiring reason and becoming man, by means of language proceeding from primitive rudiments, they were, nevertheless, satisfied to assume the privileged position of man as an absolute endowment, or a self-evident axiom. This continued as long as natural science was limited to a merely superficial classification of organisms.

Man, as consisting of flesh and blood, seemed, indeed, akin to the higher animals; but so long as their descent, their actual consanguinity was not discussed, so long as nothing was demanded beyond their juxtaposition, according to the analogy of their characteristics, without any scrutiny of the deeper causes of their divergence or similarity, man indisputably occupied the highest grade in the system of living beings. Linnæus places man in the order of Primates, together with bats, lemurs, and apes, without, on that account, being accused from pulpit and from chair of an assault on the dignity of mankind. Buffon, likewise, was able, unrebuked, to indulge his whim, by specially discussing our race in his description of the ass.

Only when, quite recently, the world became aware that the word "affinity," hitherto uttered with supreme. indifference, was henceforth to be taken seriously and literally, since that which is akin is also the fruit of one and the same tree, a beam of joyful recognition thrilled

through those to whom man appeared a being completely within the bounds of nature. But others, who can think of man only as a being absolutely endowed above his natural surroundings, could not fail to regard as a sort of crime the deduction which an all-embracing theory applied with relentless logic to man.

The interest with which the modern theory of kindred and descent has been received does not, therefore, proceed from friends alone, but quite as much from antagonists, who perceive, more or less distinctly, the danger with which the new doctrine threatens their standpoint of miracle.

Even in England the opposition to the great Englishman, with whose name the revolution is connected, has been very considerable, especially since it became evident that, true to himself, he includes man also within the range of his researches, and purposes to apply to him all the consequences of his doctrine. But it appears to me that the dispute and the agitation are still keener on this side of the channel, where Darwinism is meat and drink to the daily papers, and to the philosophical and theological periodicals.

This phenomenon is obvious to all eyes, and we are convinced of the deep importance of the subject which, whether we take part for, or against it, must influence our whole theory of life. Here too that has happened to many, which so often happens in questions the difficulties of which are veiled by an apparent general familiarity. Every one thinks himself capable of deciding about life, and, since to non-scientific persons the notorious relationship with apes is the alpha and omega of the doctrine of Descent-since the most

REFERENCE TO DARWIN.

7

confused heads are often most thoroughly convinced of their own pre-eminence-on no subject do we so frequently hear superficial opinions, mostly condemnatory, and all evincing the grossest ignorance.

I wish then to render the reader able to survey the whole ramified and complicated problem of the doctrine of Descent, and its foundation by Darwin, and to enable him to understand its cardinal points. But we must first dispose of a preliminary question of universal importance and special significance, which is frequently ignored by philosophical and theological opponents, that is, the question of the limits of the investigation of nature. of nature. For if it were an established principle that the mystery of the living is different from that of the non-living, that the former might be disclosed, but that the latter is shrouded in a veil which never can be raised, as is even now so frequently asserted, then, indeed, all research directed towards the comprehension of life would be utterly vain and hopeless.

But if the possibility of investigating life and its origin be not opposed by any à priori scruples, still more, if the limits of investigation and knowledge, which undoubtedly exist, are no other for animate nature than for the inanimate world of matter, we may venture to approach our task. This will be most adequately effected by making ourselves somewhat familiar with the object of the doctrine of Descent, restricting ourselves, however, to the animal world. If I say then that we must obtain a foundation for the theory of derivation or descent, for the doctrine of the gradual and direct development of the higher and now-existing organisms from lower ancestral forms-in short, for the doctrine of the continuity of

life, we must begin with a survey of the animal forms now spread over the earth. As astronomy begins with the mere classification of the stars and constellations, and the knowledge of their apparent motions, so do we also range our material in large groups, and this in the manner offered by the historical development of science.

What first strikes the observer of the animal world is, that it consists of apparently innumerable forms. The primary requirement is discrimination and arrangement. In the first stages of their development, zoology, as well as botany and mineralogy, necessarily consisted of mere descriptions, of a knowledge of objects in a state of completeness. Physics and chemistry, on the other hand, deal with the investigation of phenomena. directly referring to their origin, that is to say, with series of phenomena mutually connected as causes and effects, the knowledge of which, therefore, leads at once to results satisfactory and tranquillizing to the mind. This description, at first limited to the exterior, was gradually extended to the interior, because zootomy and comparative anatomy, even more than fifty years ago, had advanced so far in the accumulation of endless details that Cuvier then ventured to found the Natural System.

But this delineation of the animal world required completion on two sides, and, as the science proceeded towards perfection, it received it almost simultaneously on both. To the knowledge of the existence of an animal belongs also the description of its origin. I say emphatically, "the description," for the history of animal development is not as yet in itself a natural science in the same sense as the mathematico-physical

COMPARATIVE ANATOMY AND EVOLUTION.

A

B

9

sciences; it is a mere description of nature. But it yields a far more accurate knowledge. In many cases. it discloses, for the first time, the significance of organs, and gives to comparative anatomy the confirmation, and frequently the possibility of interpretation. The wing of a bird, in its individual parts, may be traced back without difficulty to the anterior extremities of a reptile or a mammal. But the leg of a bird, as a complete organ does not harmonize with the leg of other vertebrata until the development of the bird in the egg reveals that the disposition of the segments and of the articulations is precisely the same in both cases, and that the apparent anomaly is produced merely by the subsequent anchylosis of bones, which generally remain separate.

The complete leg of the bird (A) shows us at a, the femur, or thigh bone, and at b, the tibia, or lower leg bone; but instead of the bones of the tarsus and metatarsus, the latter of which

affords attachment to the

b

FIG. I.

m

b

toes, we find only the long bone c, and at its lower