Heredity and the Origin of Variations. 157 



I do not know that Professor Weismann has anywhere 

 distinctly stated what he conceives to be the relation of 

 body-plasm and germ-plasm in the protozoa. Are the two 

 as yet undifferentiated ? This can hardly be so, seeing the 

 fundamental distinction he draws between them. Is it 

 the germ-plasm or the body-plasm that is influenced by 

 external stresses? If the former, does it transfer its 

 influence to the body-plasm during the life of the indi- 

 vidual? If the latter, then the body-plasm must either 

 directly influence the germ-plasm in unicellular organisms 

 (it would seem that, according to Professor Weismann, it 

 cannot do so in the metazoa), or the changed body-plasm, 

 which shares in the fission of the protozoon, must participate 

 in that so-called immortality which is often said to be the 

 special prerogative of germinal matter. 



These, however, are matters for Professor Weismann 

 and his followers to settle. I regard the sharp distinction 

 between body-plasm and germ-plasm as an interesting 

 biological myth. For me, it is sufficient that the proto- 

 plasm of the protozoon is modified, and the modification 

 handed on in fission. And it is clear that Professor 

 Weismann is correct in saying that the commixture or 

 combination of characters takes its origin among the 

 protozoa. If the unicellular individuals are differently 

 modified, however slightly, then, whenever conjugation 

 occurs between two such individuals, there will be a com- 

 mingling or combination of the different characters. The 

 transmissible influence of the environment, however, ceases 

 when the metazoon status is reached, and special cells are 

 set apart for reproductive purposes — ceases, that is to say, 

 in so far as the influence on the body is concerned. There 

 may, of course, be still some direct* influence on the 

 germinal cells themselves. Except for this further in- 

 fluence, the metazoon starts with the stock of variations 



* Darwin spoke of changed conditions acting " directly on the organization 

 or indirectly tlirough the reproductive system." Now, since Professor "Weis- 

 mann has taught us to reconsider these questions, we speak of such conditions 

 as acting directly on the germ or indirectly through the body. The germ is 

 no longer subordinate to the body, but the body to the germ. 



