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THE POPULAR SCIENCE MONTHLY. 



associated primitive ideas of the divine 

 mind and will — crude cosmogonies current 

 at the beginning of recorded human ob- 

 servation. Conceptions, transient in char- 

 acter, have had alliance with reli_ious sen- 

 timents, essentially permanent. When a 

 traditional cosmogony, such as the Mosaic, 

 is transmitted as of equal sacredness with 

 religion, there is grave danger that science, 

 in discrediting the cosmogony, may do hurt 

 to religion. This danger is avoided when 

 we discriminate between the transient and 

 permanent elements in theology. There is 

 not, and never was, any necessary connec- 

 tion between any theory of Nature's history 

 and the kernel of religion — the sense of a 

 supreme mystery behind Nature, the sense 

 of , moral obligation transcending utihty, 

 and the hope of everlasting life. The con- 

 flict which so many suppose to be between 

 religion and science is more and more seen 

 to be really between new science and old — 

 if by stretch of courtesy primitive observa- 

 'tion and theorizing can be called science at 

 all. Timidity, half informed and careless 

 in discrimination, imagines science to be 

 intent on destroying the temple of religion, 

 whereas its chief est mission is to broaden 

 and heighten it. The more intelligible Na- 

 ture becomes to the student, the profound- 

 er his reverence for the Intelligence mani- 

 fested in Nature, Evolution, as a philoso- 

 phy, deals only with the history of Nature, 

 not its origin ; with its transformations, not 

 its essence, 



■ That evolution is truth, and axiomatic 

 truth, Prof. Le Conte firmly maintains. Ilis 

 presentation of its proofs, though rapid, is 

 masterly, and brought down to date. lie 

 sets forth the important and little appre- 

 ciated work of Agassiz in this connection — 

 his proof that the laws of embryonic devel- 

 opment are also the laws of geological suc- 

 cession. Agassiz, however, holding as he 

 did the doctrine of permanency of specific 

 types, rejected the theory of the derivative 

 origin of species. Prof. Le Conte then pre- 

 sents the factors of evolution tersely and 

 concisely — the effects of physical environ- 

 ment, of the use and disuse of organs, of 

 natural, sexual, and physiological selection. 

 He brings forward evidence for evolution 

 from the general laws of animal structure, 

 incidentally discriminating between analo- 



gies and homologies. He compares the 

 forelimbs of mammals, birds, reptiles, and 

 fishes, part for part, in a specially able man- 

 ner. Embryology is next summarized in 

 proof of the derivative origin of specific 

 forms, and the parallel between the devel- 

 opment of an individual and of the species 

 to which the individual belongs is brought 

 out very forcibly. The significance of rudi- 

 mentary organs — teeth in whales, the caecum 

 in man — is shown to depend solely on de- 

 scent from forms wherein such organs were 

 useful. Unexercised, they have dwindled, 

 and tend to disappear. Evolution is next 

 shown to be supported by the facts of geo- 

 graijhical distribution. Isolation of the 

 Australian continent at a remote geological 

 era explains the primitive characteristics of 

 its fauna and flora. The peculiarities of 

 island-life, the rapid changes in organic 

 forms during the last glacial epoch, and the 

 recession of arctic species to the snow-line 

 of the Alps and the high mountains of Colo- 

 rado and California, are shown to be intel- 

 ligible on no other hypothesis but that of 

 evolution. Prof. Le Conte next surveys the 

 testimony drawn from the artificial produc- 

 tion of varieties, and presents with graphic 

 illustration the law of cross-breeding. 



While maintaining that the fact of evo- 

 lution is certain, our author points out that 

 all its laws are not yet fully understood. 

 Among the difficulties which he considers 

 are those of the uselessness in incipient 

 stages of organs afterward developing into 

 usefulness. In such stages, for example, 

 fins probably commenced as buds from a 

 trunk ; it is difficult to see how as buds 

 they could be of any use, and therefore 

 how they could be improved by natural se- 

 lection until they grew to efficient size, and 

 especially until muscles were developed to 

 move them. Again, in the case of a va- 

 riety in a new and useful direction making 

 its appearance, what has prevented its oblit- 

 eration by cross-breeding with the parental 

 form ? Thus, while he holds the law of 

 evolution to be even more surely demon- 

 strated than the law of gravitation, Prof, 

 Le Conte points out problems to which stu- 

 dents may most profitably direct their pow- 

 ers of observation and generalization. 



Because our author is thoroughly a man 

 of science, he finds his knowledge in con- 



