PLANT AFFINITIES 231 



these intimate chemical conditions, then the same 

 thing may well be supposed to be true of plants. 

 And so the affinity shown between species that 

 can be crossed, and the antagonism between 

 species that refuse to cross can be explained on 

 the basis of a fundamental intrinsic quality of 

 the protoplasm, the foundation substance of life. 



This gives us a more profound and compre- 

 hensive appreciation of the word "affinity" as 

 applied to various species of plants than we 

 could otherwise have. 



It also makes it in a measure comprehensible 

 that the traits of remote ancestors should be 

 carried latent in the tissues of the germ plasm, 

 as we have seen that they are carried, for un- 

 told generations. 



THE CONTINUITY OF THE GERM PLASM 



This germ plasm, which is the connecting link 

 between one generation and another, is passed on, 

 according to the most prevalent idea, from 

 parent to offspring, generation after generation, 

 subject only to such modifications as may from 

 time to time be imposed through environing 

 influences. 



The physical mechanism that underlies this 

 transfer we shall have occasion to examine in 

 another connection when we discuss at some 



