563 



THE AMEBIC AN NATURALIST [Vol. XLVILI 



A conclusion so radical and so opposed to previous work 

 should not be accepted, however, as long as it remains at all 

 reasonably possible to use instead an explanation in harmony 

 with the results of Johannsen and other investigators. Johann- 

 sen dealt with a character— dimensions of seed— which must be- 

 yond any doubt have been partially dependent upon a very great 

 many factors, yet he found that selection had no effect whatever 

 after he had separated the different genotypes from one another. 

 Thus he proved the constancy of a great many genes "at one 



not variation, of genes. All our evidence points to the conclusion 

 that the vast majority of genes are extremely constant, although 

 they differ somewhat in that very slight amount of variation 

 which they do show. For example, in Droxopli ihi, although in 



found, yet in one case (possibly in two or three cases) a locus has 

 mutated three times, each time in a different way, thus giving 

 rise to a system of multiple allelomorphs containing four mem- 

 bers. This gene evidently is more subject to mutation than the 



