184 An Examination of Weismanntsm. 



all those theories of heredity to the family of which pan- 

 genesis belongs. All these theories go upon the assumption 

 that living material has been continuous in telluric time — 

 i.e., always derived from pre-existing material of the same 

 kind ; but they embody the further assumption that all living 

 material is material of the same kind — i.e., everywhere 

 presents the same fundamental properties. Weismann's 

 theory on the other hand, while adopting the first assump- 

 tion, rejects the second ; and assumes in its stead that living 

 material exists in " two kinds," only one of which has been 

 continuous, while the other is discontinuous — being, in fact, 

 formed anew at each ontogeny. Therefore, to my mind, it 

 seems more needful to argue the point wherein his theory 

 differs from these other theories of heredity, than it is to 

 argue the point wherein it agrees with them. We look to 

 him for a proof of the discontinuity of somato-plasm much 

 more than we do for a proof of the continuity of germ-plasm. 

 Now the only proof that he has to give of the discontinuity 

 of somato-plasm — or, in other words, that the self-multiplica- 

 tion of somatic cells cannot take place unless the nucleus of 

 each contains a self-multiplying idio-plasm derived from the 

 nucleus of a germ-cell — is the non-transmissibility of somato- 

 genetic characters. Here, however, there is an obvious 

 equivoque. For his only test of characters as somatogenetic 

 and blastogenetic consists in observing whether or not they 

 are inherited : if they are inherited, he says they are blasto- 

 genetic : if they are not inherited, he says they are somato- 

 genetic. But this is manifestly circular reasoning, so long 

 as the question in debate is as to the truth of his theory. 

 What we require in proof of the distinguishing feature of that 

 theory— i.e., the discontinuity of the hypothetical somato- 

 plasm — is not merely the obvious fact that some characters 

 are inherited while others are not, but independent proof 

 that inherited and non-inherited characters correspond to 

 a continuity of germ-plasm on the one hand, and a dis- 



