Weismannism up to date (1893). 169 



genital variations from the first origin of sexual 

 propagation. 



2. On the contrary, as all such variations have 

 been originated by the direct action of external 

 conditions, the continuity of germ-plasm in this sense 

 has been interrupted at the commencement of every 

 inherited change during the phylogeny of all plants 

 and animals, unicellular as well as multicellular. 



3. But germ-plasm remains continuous in the 

 restricted, though still highly important sense, of 

 being the sole repository of hereditary characters of 

 each successive generation, so that acquired characters 

 can never have been transmitted to progeny " repre- 

 sentatively," even although they have frequently 

 caused those " specialized " changes in the structure 

 of germ-plasm which, as we have seen, must certainly 

 have been of considerable importance in the history 

 of organic evolution. 



4. By surrendering his doctrine of the absolute 1 

 stability of germ-plasm on the one hand, and of its 

 perpettial 1 continuity on the other, Weismann has 

 greatly improved his theory of heredity. For, what- 

 ever may be thought of his recent additions to this 

 theory in the way of elaborate speculation touching 



1 I find that a passage explaining the sense in which I use these terms 

 has been accidentally omitted from Chapter III, where they are first 

 introduced ; and, as the sheets of that chapter have been already printed 

 off, I here supply the omission. The terms in italics are not Weismann's, 

 and I have employed them merely for the purpose of giving precision to 

 his views. By " absolute stability of germ-plasm " I mean to indicate 

 that degree of stability which he has hitherto postulated as the necessary 

 basis for his doctrine of heritable variations being solely due to admix- 

 tures of germ-plasm in sexual unions. By "perpetual continuity of 

 germ-plasm" I intend to denote that amount of continuity which he still 

 postulates as the necessary basis for his correlative doctrine touching the 

 non-inheritance of acquired characters. 



