575. 37 



IV. 



Cope's '' Factors of Evolution. "' 



■^PHE object of this book is *' to select from the mass of facts 

 1 accumulated by biologists, those which, in the author's opinion, 

 throw a clear light on the problem of organic evolution, and especially 

 that of the animal kingdom." The selection, however, is chiefly 

 made from the facts of palaeontology, with a view to interweaving 

 them with the evidence from bionomics and embryology that has been 

 set forth by others. The author poses not as a judge, but as an 

 advocate, and the evidence that he marshals is intended to prove the 

 following propositions: (i) Variations appear in definite directions; 

 (2) Variations are caused by the interaction of the organism and its 

 environment ; (3) Acquired variations (which I shall call modifica- 

 tions) are inherited ; (4J Variations survive directly as they are 

 adapted to changing environments ; (5) Movements of the organism 

 are directed by sensation and other conscious states ; (6) Habitual 

 movements are derived from conscious experience ; (7) The rational 

 mind is developed by experience, through memory and classification. 



Natural selection, then, is admitted by thesis 4, but, according to 

 the other theses, is left little work to do. For, if variation be definite, 

 if it, whether as congenital variation or as inheritable modification, be 

 induced by change of environment, or be, as theses 5 and 6 seem to 

 imply, a more or less conscious response thereto— then, if this method 

 of evolution be a workable method at all, it is a self-sufficient method. 

 Natural selection, if these six theses be true, will find no variations 

 out of harmony with the environment, and will have to seek a 

 situation in another universe. But one can admit the truth of all 

 these propositions without admitting it to be the whole truth. There 

 might still be variations that were indefinite and not in directions 

 determined by environment, modifications that were not inherited, and 

 movements that were not the result of consciousness in any accepted 

 sense of the word. The march of events is not bound to be on any 

 simple system dreamt of in our small philosophies. In short the 

 Neo-Darwinian is not compelled to cut the throat of the Neo- 

 Lamarckian, but may join the agnostics, of whom there are still a 



iThe Primary Factors of Organic Evolution. By E. D. Cope. 8vo. Pp, xiv., 

 548, and 121 text-figures. Chicago and London: Tiie Open Court Publishing Co. 

 1896. Price 2 dols. 



