The immeasurable step which Darwin thus made in organic morphology can be adequately appreciated only by those who, like myself, were brought up in the school of the old teleological morphology, and whose eyes were suddenly opened by the theory of selection to a comprehension of that greatest of all biological riddles, the creation of specific forms. The dogma of creation, the mystic and dualistic doctrine of the isolated creation of each separate variety, was annihilated at one blow; the belief in transmutation has now for ever taken its place—the mechanistic and monistic doctrine of the metamorphosis of organic forms, of the descent of all the species of one natural class from a common parent-form. How complete a change the science of mechanical morphology has by this means been compelled to undergo, I have endeavoured to point out in my "General Morphology;" and any one who wishes to convince himself clearly of what an enormous revolution has been brought about, particularly in comparative anatomy, may compare the "Outlines of Comparative Anatomy" (Grundzüge der vergleichenden Anatomie), by Carl Gegenbaur, 1870, and the latest edition of his "Elements" (Grundrisses), with the old text-books of that science.
Virchow has no suspicion even of all these immeasurable strides in morphology, for this department always lay out of his ken. His great reforms in pathology were founded in the province of physiology, and more especially in cellular physiology. But within the last twenty years these two main branches of biological inquiry have grown more and more apart. The great Johannes Müller was the last biologist who was able to keep these departments of organic inquiry together, and who won equally immortal honours in both divisions of the subject. After Müller's death in 1858 they fell asunder. Physiology, as the science especially of the functions or living activity of the organism, addressed itself more and more to exact and experimental methods: morphology, on the contrary, as the science of the forms and structure of animals and plants, could naturally make but very small use of this method; it must take refuge more and more in the history of evolution, and so constitute an historical natural science. It was on this very historical and genetic method of morphology, in contradistinction to the exact and experimental method of physiology, that I based my Munich address; and if Virchow in his answer had really and thoroughly refuted this position, instead of fighting with mere phrases and denunciations, this radical opposition would have been well worthy of the fullest discussion. At the same time I have no wish to reproach Virchow for being wholly fettered by the one-sided views of the modern school-physiology, nor because morphology lies so far out of his ken that he has not been able to form an independent judgment of its aims and methods; but when, in spite of all this, he on every occasion lets fall a disparaging judgment of it, we must dispute his competence. It is true that in his Munich address he emphasises the statement, "That which graces me best is that I know my ignorance," by printing it in italics. I only regret that I am forced to deny his possession of this very grace. Virchow does not know how ignorant he is of morphology, else he would never have uttered his annihilating verdict on it, else he would not continually designate the study of the theory of descent as dilettanteism and vain dreaming, as "a fanciful private speculation which is now making its way in several departments of natural science." In truth, Virchow does me greatly too much honour when he designates as my "personal crotchet" an idea which for the last ten years has been the most precious common possession of all morphological science. If Virchow were not so unfamiliar with the literature of morphology, he must have known that it is penetrated throughout by this principle of descent, that every morphological inquiry which conscientiously pursues a well-considered problem now assumes the doctrine of descent as granted and indisputable. Of all this he is ignorant, and so it is intelligible that he should continue to demand "certain proofs" of this hypothesis, although those proofs have long since been produced.
[12] Vol. ii., p. 334 of translation.
[13] London: C. Kegan Paul & Co. 1879.
[14] Jena, Zeitschriften für Naturwissenschaft, 1875. Vol. x. Supplement.
CHAPTER III.
THE SKULL THEORY AND THE APE THEORY.
Inasmuch as Virchow persists in treating the theory of descent as an "unproved hypothesis," inasmuch as he ignores all the forcible evidences of that hypothesis, he deprives himself of the right of speaking a decisive word in this, the most important scientific dispute of the present day. Virchow is, in fact, simply incompetent in the great question of evolution, as he is deficient in the greater part of that knowledge—more especially morphological knowledge—which is indispensable to forming a judgment upon it. Hence on the turning-point of the whole matter—viz., the problem as to the origin of species—he can have no opinion, as he has never turned his attention to the systematic treatment of species: those transitions of one species into another, which he asks to see, abound on all sides, as is well known to every systematic naturalist. Only consider, for example, the genera of Rubus and Salix among the living plants of the present period, and the Ammonites and Brachiopoda among extinct animals. Hence, too, Virchow can have no independent views as to the historical development of the higher from the lower animals, because the abundant living forms of the lower animals are almost unknown to him, and because he has hardly any conception of the marvellous strides which hundreds of industrious workers have made in this very department within the last twenty years. But there can be no doubt, indeed it is already universally acknowledged, that it is precisely the comparative anatomy of the lower—nay, of the very lowest animals—that has solved the greatest riddles of life, and removed the greatest obstacles from the path of the doctrine of descent. He simply ignores the fact that true Monads actually exist, and have been positively identified by many different observers as structureless "organisms without organs," and he turns out the poor Bathybius with a kick. And yet I believe that in "Kosmos"[15] I have conclusively proved that Monads must retain their vast elementary importance whether the Bathybius actually exists or not.