CHAPTER VI. 



HOW TO GET AT THE CONSTITUTION OF 

 THE GAMETES. 



It is perfectly correct that the constitution of the 

 gametes is basic to all questions of heredity, and may 

 have to do, not only indirectly as it certainly does, but 

 also directly, with the question of the origin of species. 



de Vries showed great insight in questions of evolu- 

 tion by maintaining that the final cause of the origin of 

 species lies in the constitution of the gametes, but his 

 mistake (Quis caruit erroribus?) was that he overloo- 

 ked the fact, that the cause of evolution does not neces- 

 sarily lie in the behaviour of a single gamete, but might 

 lie — as it does in my opinion in diploid species at 

 least — in the interaction of two gametes of different 

 constitution. 



That we complicate matters— probably unnecessarily 



— by trying to get at the constitution of the gametes, 

 through the study of diploid organisms, is plain ; we 

 ought to begin with the study of haploid organisms. 



Among these, mosses offer special advantages becau- 

 se the mossplant — being the haploid generation — is 

 the result of a single gamete, while the higher plants 



— being diploid generations — are the result of the 

 interaction of two gametes. 



If therefore, we ever succeed in changing the consti- 

 tation of a gamete experimentally, the result will be 



