EVOLUTION 121 



sudden changes, or mutations as they have 

 been called, and which, since the revival of 

 Mendel's work, have been found to occur in 

 most animals and plants. These differences, 

 like Minerva, are born in their fullness, and 

 selection may act upon them at once. Thus it 

 is well known that from time to time albino 

 individuals appear in stocks of wild as well as 

 of domesticated animals. Such an appearance 

 is a mutation, and in the case of wild animals 

 living in a district where dark coloration is of 

 protective importance, the individuals bearing 

 this trait would probably be quickly exter- 

 minated ; but in an environment like the 

 polar regions where whiteness is an advan- 

 tage, such individuals might well be preserved 

 and in the end give rise to a white stock. 



Such hypothetical cases show us how nat- 

 ural selection may take place, and yet we have 

 reason to suspect that the process itself is not 

 so simple. Selection is supposed to act on what 

 Weismann might call the somatic qualities of 

 individuals, coat-color, size of body, strength 

 of muscle, and so forth, and it is assumed that 

 these traits, since they are germinal in origin, 

 would be reproduced in the offspring. But, as 

 we saw from the breeding experiments with 



