WHAT EVOLUTION IS 143 



heritance, and such a condition, if at 

 all general, would be very restricting 

 to the mutation view. 



Mutations further give the impres- 

 sion of laboratory and of garden 

 products, rather than of products of 

 the land and sea. Mutations certainly 

 occur in nature, witness albino ani- 

 mals, but the experimental product 

 seems to be far removed from what 

 is demanded by open nature. Many 

 workers have been so impressed with 

 this aspect of the question, that they 

 have come to look upon the great 

 biological advance of the last two 

 decades as illuminating, from the 

 standpoint of heredity, but as having 

 very little real bearing on the evolu- 

 tion problem. The truth is that the 

 mutation idea, and all its intricate 

 connections, are somewhat too novel 

 to admit of final judgment. 



What the factors of evolution are. 



