158 THE EVOLUTION THEOEY 



We mud assume determinants, and consequently the germ-plasm 

 must have room for these ; the variations of species can only be 

 explained through variations of the germ-plasm, for these alone give 

 rise to hereditary variation. It is upon this foundation that mj^ 

 germinal selection is built up : whether I have in the main reached 

 the truth the future will show : but that I have not exhausted this 

 new domain, but only opened it up, I am verj^" well aware. 



