Art and Science 



they do this they have knocked the bottom 

 out of their case. 



From among the passages in which Pro- 

 fessor Weismann himself shows a desire to 

 hedge I may take the following from page 170 

 of his book : 



" I am also far from asserting that the 

 germ-plasm which, as I hold, is transmitted 

 as the basis of heredity from one generation 

 to another, is absolutely unchangeable or 

 totally uninfluenced by forces residing in the 

 organism within which it is transformed into 

 germ-cells. I am also compelled to admit it 

 as conceivable that organisms may exert a 

 modifying influence upon their germ -cells, 

 and even that such a process is to a certain 

 extent inevitable. The nutrition and growth 

 of the individual must exercise some influence 

 upon its germ-cells ..." 



Professor Weismann does indeed go on to 

 say that this influence must be extremely 

 slight, but we do not care how slight the 

 changes produced may be provided they exist 

 and can be transmitted. On an earlier page 



(p. 101) he said in regard to variations gener- 



283 



