CONTEOL 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 '. 



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 natiu-alists, especially 

 the students of plant oecology,^ 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'.^ 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. 



' See J. M. Coulter in Fifty Years of Danoinism, New York, 

 1909, 61-3. 

 ^ Editors of More Letteis, i. 214 n. 1. 



