CONTROL OF NUPTIAL PLUMAGE 143 



the winter season had been skipped.' The author 

 justly claims to have established 'that the se- 

 quence of plumage in these birds is not in any 



way predestined through inheritance , but 



that it may be interrupted by certain factors in 

 the environmental complex '. -<l*l 



Mr. Beebe's deeply interesting investigations on 

 birds prove that external stimulus may be as 

 necessary for the production of the tints displayed 

 in courtship as for other colours that are character- 

 istic of the species (p. 1 10). Birds may thus exhibit 

 the individual susceptibility to environment so 

 well known in numbers of insect larvae and pupae 

 (p. 109). Although certain naturalists, especially 

 the students of plant oecology, 1 consider that re- 

 sults of this kind are opposed to a Darwinian 

 interpretation, it is perfectly clear that * the 

 changes so produced must, like any other varia- 

 tions, pass through the ordeal of the survival of 

 the fittest'. 2 And when each possible response 

 is appropriate to the special environment which 

 provides the stimulus, it is obvious that, so far 

 from witnessing the elimination of Natural Selec- 

 tion, we are in presence of its highest manifesta- 

 tion. 



1 See J. M. Coulter in Fifty Years of Darwinism, New York, 

 1909, 61-3. 



2 Editors of More Letters, i. 214 n. 1. 



