EVOLUTION OP THE COLORS OF BIRDS. 91 



during the breeding season, which is due to the state of 

 their nervous organization, and granting, even, that the 

 excitement shown by birds at this time may be due to 

 the same cause, to a large extent, this does not account 

 for the fact that the male birds display their ornaments 

 in a painstaking and elaborate way. Prof. Beddard 

 states Mr. Stolzmann's view as set forth in the Proceed- 

 ings of the Zoological Society.'^ This theory is indeed an 

 ingenious one and may be used as supplementary to the 

 theory of sexual selection. It is based upon the assump- 

 tion that male birds are much more numerous than the 

 females, an assumption which Mr. Wallace rather too 

 hastily discarded. Mr. Stolzmann suggests that this 

 preponderance of male birds would be a disadvantage to 

 the species, for the unpaired males would be apt to 

 annoy the setting females and prevent the raising of the 

 brood. Accordingly those species in which the males 

 greatly predominated would stand less chance of per- 

 petuating their kind than species in which the sexes 

 were more evenly divided, and any device by which the 

 surplus males could be killed of! would enable such as 

 were left to rear their offspring with greater success. 

 Such a device is to be found, according to Mr. Stolz- 

 mann's view in the long tail feathers and brilliant 

 colors of many male birds. If Mr. Stolzmann's view 

 be correct then natural selection, it Avould appear, 

 must be causing individuals to assume instruments for 

 their own destruction in order that the species may live. 

 This conclusion is arrived at from a merely superficial 

 consideration of the case, however. Natural selection 

 is in reality only preserving the lives of the greatest 

 number of individuals. In any given generation the 

 fittest individuals to survive would be those males which 

 were least ornamented, but these would be the least fit to 



* 1885, p. 615. 



