So EXPERIMENTAL EVOLUTION LECT. 



character, or at least it -must be one to most of the 

 present systematic naturalists (though I doubt if this 

 state of things is eternal), and as evolutionists, we 

 cannot allow this character to be lightly disposed of, 

 when it is precisely one of the most variable in some 

 cases. 1 In some cases, I repeat, not in all. For 

 while some instances of colour variation may be 

 observed in the state of nature among animals or 

 plants, while some special variations are more especially 

 met with, such as albinism and melanochroism, it must 

 be noted that colour variations are especially frequent 

 among cultivated plants and domestic animals, and are 

 thus due to the results of changing environment. We 

 do not always perceive how far there may be a change 

 in environment, but colour variations show that it 

 exists in many cases where we do not readily detect it. 

 Among animals in their natural condition, colour 

 variations are of no very rare occurrence. It is known 

 that the common fox in the same country offers 

 marked variations in colour, which are illustrated by 

 the different names which have been conferred upon 

 the principal forms ; Vulpes alopex, melanogaster, and 

 crucigera. The beaver also offers important colour 



1 Of course facts concerning colour variation are to be found in a 

 large amount of works. But I would recommend, concerning colour 

 variation in insects, two recent works. The one is Mr. S. H. Scudder's 

 magnificent work on the Butterflies of New England ; the other is the 

 Entomologist' s Record and Journal of Variation. 



