282 DARWINISM TO-DAY. 



mined not at all, at least in their beginnings, by selection on 

 a basis of utility, but as the result of the inheritance of ac- 

 quired characters and according to the laws 

 of or g anic growth (organophysis). The prin- 

 cipal effects of these laws of organic growth are 

 made manifest by the determinant evolution, or orthogenesis, 

 which obtains, and which is in direct contrast to that kind of 

 evolution which natural selection, if it really effected any- 

 thing, would bring about. For evolution by natural selec- 

 tion would occur along all sorts of heterogeneous and radiat- 

 ing lines which is, according to Eimer, actually not the 

 case. A few definite lines obtain from which occasional 

 branches are given off, the whole building the familiar 

 phyletic or genealogical tree. That these main lines and 

 branches are not themselves the result of selection is proved 

 by the fact that much evolution and modification of organ- 

 isms is not directly useful, a majority, indeed, of the char- 

 acters distinguishing different species not being characters 

 of utility. 17 Only when a character or line of evolution 

 becomes of a life-and-death-determining disadvantage can 

 selection interfere with evolution by orthogenesis. And this 

 interference is always and only of the nature of a stamping 

 out, never of the character of the creation of new characters 

 or lines. Eimer believes in the inheritance of acquired 

 characters, believes in a considerable species-forming influ- 

 ence of geographical isolation, that is, finds such isolation 

 very helpful to the general basic organic growth evolution 

 principle and finds the actual causes of orthogenesis "to 

 lie in the effects of external influences, climate, nutrition, 

 on the given constitution of the organism." "This is not 

 Lamarckism," Eimer points out, anxious to have his theory 

 to his own credit, "for Lamarck ascribed to the external in- 

 fluences no effects on the animal body, and only very little 

 on the plant body." Eimer adds that the effects of external 

 influences are usually considered a part of Lamarckism; 



