52 HEREDITY 



mean the environment other than the individual 

 body) upon the germ -plasm, such an assumption 

 being unsupported by evidence. 



Yet a third suggestion, as we have seen, must be 

 rejected in consequence of the work of the last 

 decade. We must reject as incompatible with the 

 facts the theory of Weismann that the great cause of 

 variations is amphimixis or bi-parental reproduction. 

 We must reject this theory despite its apparent 

 adequacy and its attractiveness, and despite the fact 

 that, having rejected it, we are almost at our wits' 

 end for a better. 



Let us see how the difficulty is met by Archdall 

 Reid, after his brilliant exposition of the evidence 

 which has led to the rejection of Weismann's theory. 

 He declares that spontaneous variations are due 

 "undoubtedly to an inborn tendency to vary, a 

 tendency that is inherent in the germ-plasm of every 

 species of plant and animal." Certainly Mr. Reid 

 does not offer this answer without an attempt to 

 explain the origin and cause of this tendency, but 

 after the most careful study of his speculations, ^ I 

 confess that they afford me no satisfaction, and I 

 cannot persuade myself that they are worth quoting. 

 When we come to the summary of the first section of 

 his work, we read : — 



" IV. A progressive variation constitutes a deviation 

 from the parental and ancestral type, which, speaking 

 generally, is in the direction of increased magnitude and 

 complexity. It results from the complete recapitulation 

 of the parental development plus an addition." 



1 «' 



Principles of Heredity," p. 95. 



