62 THE EVOLUTION OF LIVING BEINGS. 



And this scheme has already obtained an exagerated 

 value in the opinion of many mendelians who forget, 

 that it is, at the most, a very rough diagrammation of 

 the complicated happenings during the interaction of 

 two mixed germplasmas of different constitution, so 

 that one has even carried it forward, to interpret what 

 happens, when two germplasmas of identical consti- 

 tution fuse and concluded that every germplasm is a 

 mixture of independant hereditary units. 



Now of this we know absolutely nothing. 



The mistaken idea that organisms, showing mende- 

 lian behaviour, warrant some such kind of a conclusion, 

 arose from the fact that nearly all organisms, met with 

 in nature as well as under cultivation, man included, 

 are hybrids which were mistakenly considered to be 

 specifically pure, so that their behaviour was uncon- 

 sciously held to be that of specifically pure organisms, 

 while it was that of hybrids ; so it happened that segre- 

 gation was mistaken for heredity. 



Yet, if one wanted to make out the way in which a pure 

 human species, say one with fair hair and blue eyes, 

 transmits the fairness of its hair and the blueness of its 

 eyes to its progeny, one would get no aid whatever 

 from investigation along mendelian lines; while if 

 one investigates the transmittal of eye-color or hair- 

 color in such a society of hybrids,as we are, one finds the 

 laws by which these hybrids distribute their differently 

 constituted gametes over their offspring and is apt, if one 

 forgets the hybrid nature of one's material, to mistake 

 this distribution for heredity, and to speak of Mende- 

 lian segregation as of mendelian heredity. 



