II. Principes d’Ostéologie Comparée, ou Recherches sur l’Archétype et les Homologies du Squelette Vertébré. Par Richard Owen.—Paris.
Principles of Comparative Osteology; or, Researches on the Archetype and the Homologies of the Vertebrate Skeleton. By Richard Owen.
III. On the Nature of Limbs. A Discourse delivered on Friday, February 9, at an Evening Meeting of the Royal Institution of Great Britain. By Richard Owen, F.R.S.—London, 1849. pp. 119.
Judging whether another proves his position is a widely different thing from proving your own. To establish a general law requires an extensive knowledge of the phenomena to be generalized; but to decide whether an alleged general law is established by the evidence assigned, requires merely an adequate reasoning faculty. Especially is such a decision easy where the premises do not warrant the conclusion. It may be dangerous for one who has but little previous acquaintance with the facts, to say that a generalization is demonstrated; seeing that the argument may be one-sided: there may be many facts unknown to him which disprove it. But it is not dangerous to give a negative verdict when the alleged demonstration is manifestly insufficient. If the data put before him do not bear out the inference, it is competent for every logical reader to say so.
From this standpoint, then, we venture to criticize some of Professor Owen’s osteological theories. For his knowledge of comparative osteology we have the highest respect. We believe that no living man has so wide and detailed an acquaintance with the bony structure of the Vertebrata. Indeed, there probably has never been any one whose information on the subject was so nearly exhaustive. Moreover, we confess that nearly all we know of this department of biology has been learnt from his lectures and writings. We pretend to no independent investigations, but merely to such knowledge of the phenomena as he has furnished us with. Our position, then, is such that, had Professor Owen simply enunciated his generalizations, we should have accepted them on his authority. But he has brought forward evidence to prove them. By so doing he has tacitly appealed to the judgments of his readers and hearers—has practically said, “Here are the facts; do they not warrant these conclusions?” And all we propose to do, is to consider whether the conclusions are warranted by the facts brought forward.
Let us first limit the scope of our criticisms. On that division of comparative osteology which deals with what Professor Owen distinguishes as “special homologies,” we do not propose to enter. That the wing of a bird is framed upon bones essentially parallel to those of a mammal’s fore-limb; that the cannon-bone of a horse’s leg answers to the middle metacarpal of the human hand; that various bones in the skull of a fish are homologous with bones in the skull of a man—these and countless similar facts, we take to be well established. It may be, indeed, that the doctrine of special homologies is at present carried too far. It may be that, just as the sweeping generalization at one time favoured, that the embryonic phases of the higher animals represent the adult forms of lower ones, has been found untrue in a literal sense, and is acceptable only in a qualified sense; so the sweeping generalization that the skeletons of all vertebrate animals consist of homologous parts, will have to undergo some modification. But that this generalization is substantially true, all comparative anatomists agree.
The doctrine which we are here to consider, is quite a separate one—that of “general homologies.” The truth or falsity of this may be decided on quite apart from that of the other. Whether certain bones in one vertebrate animal’s skeleton correspond with certain bones in another’s, or in every other’s, is one question; and whether the skeleton of every vertebrate animal is divisible into a series of segments, each of which is modelled after the same type, is another question. While the first is answered in the affirmative, the last may be answered in the negative; and we propose to give reasons why it should be answered in the negative.
In so far as his theory of the skeleton is concerned, Professor Owen is an avowed disciple of Plato. At the conclusion of his Archetype and Homologies of the Vertebrate Skeleton, he quotes approvingly the Platonic hypothesis of ἰδέαι, “a sort of models, or moulds in which matter is cast, and which regularly produce the same number and diversity of species.” The vertebrate form in general (see diagram of the Archetypus), or else the form of each kind of vertebrate animal (see p. 172, where this seems implied), Professor Owen conceives to exist as an “idea”—an “archetypal exemplar on which it has pleased the Creator to frame certain of his living creatures.” Whether Professor Owen holds that the typical vertebra also exists as an “idea,” is not so certain. From the title given to his figure of the “ideal typical vertebra,” it would seem that he does; and at p. 40 of his Nature of Limbs, and indeed throughout his general argument, this supposition is implied. But on the last two pages of the Archetype and Homologies, it is distinctly alleged that “the repetition of similar segments in a vertebral column, and of similar elements in a vertebral segment, is analogous to the repetition of similar crystals as the result of polarizing force in the growth of an inorganic body;” it is pointed out that, “as we descend the scale of animal life, the forms of the repeated parts of the skeleton approach more and more to geometrical figures;” and it is inferred that “the Platonic ἰδέα or specific organizing principle or force, would seem to be in antagonism with the general polarizing force, and to subdue and mould it in subserviency to the exigencies of the resulting specific form.” If Professor Owen’s doctrine is to be understood as expressed in these closing paragraphs of his Archetype and Homologies—if he considers that “the ἰδέα” “which produces the diversity of form belonging to living bodies of the same materials,” is met by the “counter-operation” of “the polarizing force pervading all space,” which produces “the similarity of forms, the repetition of parts, the signs of unity of organization,” and which is “subdued” as we ascend “in the scale of being;” then we may pass on with the remark that the hypothesis is too cumbrous and involved to have much vraisemblance. If, on the other hand, Professor Owen holds, as every reader would suppose from the general tenor of his reasonings, that not only does there exist an archetypal or ideal vertebrate skeleton, but that there also exists an archetypal or ideal vertebra; then he carries the Platonic hypothesis much further than Plato does. Plato’s argument, that before any species of object was created it must have existed as an idea of the Creative Intelligence, and that hence all objects of such species must be copies of this original idea, is tenable enough from the anthropomorphic point of view. But while those who, with Plato, think fit to base their theory of creation upon the analogy of a carpenter designing and making a table, must yield assent to Plato’s inference, they are by no means committed to Professor Owen’s expansion of it. To say that before creating a vertebrate animal, God must have had the conception of one, does not involve saying that God gratuitously bound himself to make a vertebrate animal out of segments all moulded after one pattern. As there is no conceivable advantage in this alleged adhesion to a fundamental pattern—as, for the fulfilment of the intended ends, it is not only needless, but often, as Professor Owen argues, less appropriate than some other construction would be (see Nature of Limbs, pp. 39, 40), to suppose the creative processes thus regulated, is not a little startling. Even those whose conceptions are so anthropomorphic as to think they honour the Creator by calling him “the Great Artificer,” will scarcely ascribe to him a proceeding which, in a human artificer, they would consider a not very worthy exercise of ingenuity.
But whichever of these alternatives Professor Owen contends for—whether the typical vertebra is that more or less crystalline figure which osseous matter ever tends to assume in spite of “the ἰδέα or organizing principle,” or whether the typical vertebra is itself an “ἰδέα or organizing principle”—there is alike implied the belief that the typical vertebra has an abstract existence apart from actual vertebræ. It is a form which, in every endo-skeleton, strives to embody itself in matter—a form which is potentially present in each vertebra; which is manifested in each vertebra with more or less clearness; but which, in consequence of antagonizing forces, is nowhere completely realized. Apart from the philosophy of this hypothesis, let us here examine the evidence which is thought to justify it.