1 68 An Examination of Weismannism. 



theses touching "the significance of sexual repro- 

 duction " are not necessarily exclusive of one another : 

 the process may subserve two or more adaptive 

 purposes \ But he would be a bold man who, in the 

 present state of our knowledge, could accept unre- 

 servedly the particular view of this process which 

 Darwin so emphatically rejected ; and I think he 

 must be a biased man who could entertain for 

 an instant the modification of this view which Weis- 

 mann has now substituted. 



Thus, the Weismannian theory of evolution has 

 entirely fallen to pieces with the removal of its 

 fundamental postulate — the absolute stability of 

 germ-plasm. It only remains to mention once more 

 the effects of this removal upon the other side of his 

 system — viz., the companion postulate of the uninter- 

 rupted continuity of germ-plasm, with its superstructure 

 in his theory of heredity. 



Briefly, these effects are as follows : — 



i. Germ-plasm ceases to be continuous in the 

 sense of having borne a perpetual record of con- 



" amphimixis," and one which, shows the non-necessity of what remains 

 of Weismann's theory of polar bodies, thus — 



" There is yet another advantage in double parentage, namely, that as 

 the stirp whence the child sprang can only be half the size of the 

 combined stirps of his two parents, it follows that one half of his possible 

 heritage must have been suppressed. This implies a sharp struggle for 

 place among the competing germs, and the success, as we may infer, 

 of the fitter half of their numerous varieties." — loc. cit., p. 334. 



1 In fact, it seems to me that this is the sole supposition whereby it 

 can be held that sexual propagation has been developed both "by" and 

 il for" natural selection, in order to supply variations as material for the 

 action of this principle. Natural selection cannot thus supply the 

 conditions to its own activity, if, as Weismann supposes, there is but 

 one purpose for it to subserve (see above, pp. 13-15'!. But, if it 

 is acting for more than one purpose, the " by " and the " for " argument 

 may hold. 



