Darwinism properly so called.

The relation that these three great theories, which are frequently confounded, bear to one another may, according to the present position of science, be simply defined as follows:—I. Monism, the universal theory of development, or the monistic progenesis-hypothesis, is the one only scientific theory which affords a rational interpretation of the whole universe and satisfies the craving of our human reason for causality, by bringing all natural phenomena into a mechanical causal-connection as parts of a great uniform process of evolution. II. The theory of transmutation, or descent, is an essential and indispensable element in the monistic development hypothesis, because it is the one only scientific theory which rationally explains the origin of organic species—that is to say, by transformation—and reduces it to mechanical principles. III. The theory of Selection or Darwinism is, up to the present time, the most important of the various theories which seek to explain the transformation of species by mechanical principles, but it is by no means the only one. If we assume that most species have originated through natural elimination, we also now know, on the other hand, that many forms distinguished as varieties are hybrids between two different varieties, and can be propagated as such; and it is equally well worthy of consideration that other causes are in activity in the formation of species of which, up to the present time, we have no conception. Thus it is left to the judgment of individual naturalists to decide what share is to be attributed to natural selection in the origin of species, and even at the present day authorities differ widely on the subject. Some give it a large share, and some a very small one in the result. Moritz Wagner, for instance, would substitute his own migration-hypothesis for Darwin's theory of selection; while I regard the action of migration, which acts as isolation or separation, as merely a special mode of selection. But these differing estimates of Darwinism are quite independent of the absolute import of the doctrine of descent or of transformation, for the latter is as yet the only theory which rationally explains the origin of species. If we discard it, nothing remains but the irrational assumption of a miracle, a supernatural creation.

In this crucial and unavoidable dilemma, Virchow has declared himself publicly in favour of the latter, and against the former hypothesis. Every one who has attentively followed his occasional utterances on the theory of descent during the last decade with an unprejudiced eye and an unbiassed judgment, must be convinced that he fundamentally rejects it. Still, his dissent has always been so obscured, and his judgment on Darwinism in particular so wrapped in ambiguities, that an opportune conversion to the opposite side seemed not impossible; and many, even among those who stood near to Virchow—his friends and disciples—did not know to what point he was in fact an opponent of the evolution hypothesis in general. Virchow took the last step towards clearing up this matter at Munich; for after his Munich address there can be no farther doubt that he belongs to the most decided opponents of the whole theory of evolution, including those of inheritance and selection.

If any one still has doubts on the matter, let him read the jubilant hymns of triumph with which Virchow's friend and collaborator, Adolf Bastian, greeted his Munich discourse. This "enfant terrible" of the school—this well-nicknamed "Acting privy counsellor of the board of confusion"[10]—whose merits in involuntarily advancing the cause of metamorphism I have already done justice to in the preface to the third edition of my "Natural History of Creation"[11]—expresses himself in the "Zeitschrift für Ethnologie," which is edited by him and Virchow (tenth yearly part, X. 1878, p. 66) as follows:—"At the Munich meeting of naturalists, Virchow by a few weighty words cleared the atmosphere, which was heavy and stifling under the pressure of the incubus called Descent, and once more freed science from that nightmare which it has so long—in many opinions so much too long—allowed to weigh upon it; freed it, let us hope, once and for ever. The forecasts of this storm were discernible many years since, and its whole course has been a strictly normal one. When the germs planted by Darwin, and that promised so much, were forced into growth by a feverish, hot-house heat, and began to sprout into sterile weeds, their small vitality was plain to our eyes. So long as the waves run too high under the pressure of a psychical storm, it is almost useless to protest against it, for every ear is too much deafened by the noise all round to hear the voice of individuals. It is best to leave things to go their own way, deeper and deeper into the mire, till they come to a stand-still there of their own accord; for 'Quos deus vult perdere prius dementat.' Thus it is in this case. When the extravagances of the descent hypothesis, encouraged as they were by mutual incitement, had reached their highest pitch in the ravings that were uttered at Munich, the too pointed point broke in this superabundance of absurdity almost by its own pointedness, and so we were quit of it with one blow. Now, happily, all is over with the theory of descent, or ascent, but natural science will not on that account fare any the worse, for many of its adherents belong to her ablest youth, and as they now need no longer waste their best time on romantic schemes, they will have it to use at the orders and for the advancement of science, so as to enrich her through real and solid contributions."

Furthermore, Bastian quotes Virchow's maxim:—"The plan of organisation is immutable within the limits of the species; species is not produced from species." The fundamental teleological idea of that school, that each species has its constant and specific plan of structure, certainly cannot be more emphatically expressed. Thus it is undoubtedly certain that Virchow has become a Dualist, and is as thoroughly penetrated by the truth of his principles as I, as a Monist, am of mine. This is undoubtedly the upshot of his Munich address, though he is throughout careful to avoid acknowledging his chief standpoint in all its nakedness. On the contrary, even now he still veils his antagonism under the phrase, which is also a favourite with the clerical papers, that the theory of descent is an "unproved hypothesis." Now it is clear that this theory never will be "proved" if the proofs that already lie before us are not sufficient. How often has it been repeated that the scientific certainty of the hypothesis of descent is not grounded in this or that isolated experiment, but in the collective sum of biological phenomena; in the causal nexus of evolution. Then what are the new proofs of the theory of descent which Virchow demands of us?