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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



with its dry descriptions, gives place to the more 

 vivid history of the genealogy of classes and 

 species. 



But, whatever we may think of this enormous 

 progress of morphology, it does not of itself suf- 

 fice to explain the extraordinary influence of the 

 present doctrine of evolution upon general sci- 

 ence, or the philosophy of Nature. That influ- 

 ence depends, as we know, rather on the special 

 consequences of the theory of descent as applied 

 to man. The ancient question of the origin of 

 our own species is, for the first time, solved by 

 this theory in a scientific sense. If the doctrine 

 of evolution is true in general ; if there is, in- 

 deed, a natural and historic genealogy of living 

 beings, then man, too, the lord of creation, is de- 

 scended from the sub-kingdom Vertebrata, the 

 class Mammalia, the sub-class Placentalia, and 

 the order Monkeys. Already in 1*735, Linne, in 

 his "System of Nature," classed man with the 

 monkeys and the bats, in the order of Primates. 

 None of the later zoologists have been able to 

 separate him from the Mammalia. Conclusion : 

 this place unanimously assigned to him in classi- 

 fication means phylogenetically only one thing, to 

 wit, that he is a branch of that class of ani- 

 mals. 



In vain has every effort been made to invali- 

 date this pregnant consequence of the doctrine 

 of evolution ; vain has been every attempt at 

 making an exception in favor of man, and saving 

 him from such an ancestry ; in vain has been 

 constructed for him an ancestral line distinct from 

 the genealogical tree of the Vertebrata. The 

 phylogenetic data of comparative anatomy, on- 

 togeny, and paleontology, speak so plainly in fa- 

 vor of a unitary derivation of all vertebrate ani- 

 mals sprung from a common source, that doubt is 

 impossible. No philologist who compares the 

 German, Russian, Latin, Greek, and Sanskrit lan- 

 guages, will say that they may have sprung from 

 different sources, however great the differences 

 between them may be. Nay, all are agreed, as a 

 result of critical study of the structure and the 

 development of these diverse languages, that 

 they all descend from the Aryan or Indo-Ger- 

 tnanic. So, too, all morphologists are profoundly 

 impressed with the idea, in short convinced, that 

 all the Vertebrata, from amphioxus to man inclu- 

 sively — that all fishes, amphibians, reptiles, birds, 

 and mammals, are the descendants of one primitive 

 vertebrate. Indeed, we cannot suppose that the 

 life-conditions, varied and complex as they are, 

 which through a long line of evolutive processes 

 have led to the creation of the vertebrate type, 



have occurred more than once in the course of 

 the earth's history. 



For the subject in hand, we are concerned 

 only with man's animal origin. We therefore 

 will dwell no longer on the lower stages of our 

 genealogy. We would merely, in passing, state 

 that its upper stages are now firmly established, 

 thanks to the labors of distinguished morpholo- 

 gists, among whom Gegenbaur and Huxley hold 

 the first rank. 



True, it is still often asserted that here we 

 have to do only with the descent, the origin of 

 man's body, and not of his intellectual functions. 

 To meet this serious objection we must, first of 

 all, bear in mind the physiological fact that our 

 life is inseparably tied to the organization of our 

 central nervous system. Now, the latter is con- 

 stituted like the same system in the higher verte- 

 brates, and comes into existence in the same way ; 

 even according to Huxley's researches the struct- 

 ural differences existing between the brain of 

 man and that of the higher monkeys are much 

 less than the differences between the higher and 

 the lower monkeys. Besides, the function or 

 work of an organ cannot be thought of without 

 the organ itself, and the function always devel- 

 ops simultaneously with the organ. Hence we 

 are forced to the conclusion that our psychic fac- 

 ulties have been developed slowly, gradually, in a 

 ratio with the phylogenetic building up of our brain 



For the rest, this great question of the soul 

 comes up before us now in a very different aspect 

 from that it wore twenty or even ten years ago. 

 Under whatever form we may picture to ourselves 

 the union of soul and body, of spirit and matter, 

 it is still clear, on the theory of evolution, that all 

 organic matter at least, if not matter in general, 

 is in some sense possessed of psychic properties. 

 In the first place the progress of microscopic re- 

 search has shown that the elementary anatomic 

 parts of organs — the cells — generally possess an 

 individual psychic life. Ever since forty years 

 ago, when Schleiden proposed at Jena the cell- 

 theory of the vegetable kingdom — which theory 

 was straightway applied by Schwann to the ani- 

 mal kingdom — we ascribe to these microscopic 

 beings an individual life of their own. Cells are, 

 according to Briicke, true individuals of the first 

 (or lowest) order — elementary organisms. The 

 fruitful application made by Virchow in his " Cel- 

 lular Pathology " of the theory in question to 

 medicine in general, presupposes that the cells 

 must not be regarded as the inert, passive mate- 

 rials of the organism, but as the living and active 

 members of the same state. 



