Weismanns theory of Heredity (1891). J J 



theless think that the fact ought here to be noted. 

 For the changes which occur at puberty and after the 

 reproductive functions have ceased, as well as those 

 which may be artificially produced by castration. 

 &c, prove at any rate some extremely important 

 association between the soma as a whole and its 

 reproductive apparatus as a whole. No doubt it may 

 properly enough be answered that this proof does not 

 extend to the vital point of showing the association 

 to be between the soma as a whole, and that particular 

 part of the reproductive apparatus in which the 

 " carriers of heredity " reside — namely, the ova and 

 spermatozoa ; and, therefore, that the facts in question 

 may be due only to some changed conditions of 

 nutrition on the part of the somatic-tissues which 

 these alterations on the part of the reproductive glands 

 entail. On this account we must fully allow that the 

 facts in question are not in themselves of any con- 

 clusive weight ; but I think they are worth mentioning, 

 because they certainly seem to countenance the theory 

 which supposes some reciprocal influence as exercised 

 by the germinal elements on the somatic-tissues and 

 vice versa, rather than they do the theory which sup- 

 poses the germinal elements and the somatic-tissues 

 to have always occupied totally different " spheres." 



Here, however, is a stronger class of facts. It has 

 not unfrequently been observed, at any rate in mam- 

 mals, that when a female has borne progeny to 

 a male of one variety, and subsequently bears progeny 

 to a male of another variety, the younger progeny 

 presents a more or less unmistakable resemblance to 

 the father of the older one. Now, this is a fact to 

 which Weismann has nowhere alluded ; and therefore 



