144 Heredity and Eugenics 



to be redistributed peripherally and to reproduce the dupli- 

 cate of the particular character from which they arose. 

 If now {x) impinging upon the organism, gives {y) a new 

 variation, then new sorts of gemmules are supposed to be 

 formed, and these on being gathered up and carried along in 

 reproduction by the gametes will cause to reappear in the 

 progeny the modified character. Repeated impact of (x) 

 may, in the opinion of the adherents of the view, succes- 

 sively increase (y). All theories of the peripheral origin 

 and inheritance of variations are patterned after Darwin's 

 hypothesis, and although they have different expressions or 

 terms for the carriers of the variation: nerve force, force, 

 ions, electrolites, energy, etc., they are in essence the same 

 conception and are all operated by the same mechanism. 



Radically opposed to this theory of the peripheral origin 

 of variation is that of the central or germinal origin of varia- 

 tion, in which the cause (a*) acts upon the germ and pro- 

 duces the change in the germinal constitution which, when 

 the germ undergoes development, produces the divergent 

 character (y), the variation (Fig. 57^). 



Much logic has been expended upon this problem of 

 transmission. Weismann has made a masterly analysis 

 of the situation and can discover no reason for any con- 

 clusion other than in favor of the germinal or central origin 

 of all variations that are efficient in evolution. Spencer, 

 Cope, Eimer, Semon, Rignano, and others have tried to 

 equal Weismann's logical analysis of the problem, but 

 without any conspicuous success. The problem is one for 

 experiment and not for solution by logic. 



Very tiresome are the multitude of arguments, and the 

 arrays of "plausible instances," and of the "facts" which 

 "can only be explained" thus and so. Many times has the 



