82 THE GENETIC AND THE OPERATIVE EVIDENCE 



How can we explain the apparent discrepancy of Goodale's results? 

 In one case, the nuptial plumage was molted to nuptial plumage; in 

 the other case an eclipse plumage appeared at the breeding-season. 

 Goodale regards the latter case as a more perfect approach to the male 

 than the former, but this view undoubtedly offers serious theoretical 

 difficulties. It seems to me possible to suppose that in those cases 

 where the summer plumage appeared there was in reality enough 

 ovarian tissue (or related tissue) left after the operation to produce an 

 effect at the normal season for such ovarian tissue to become most 

 active. It might then suffice to ecUpse the male plumage suflSciently 

 to make it very similar to the eclipse of the normal male. At any rate, 

 on this basis we have a consistent explanation of the entire complex 

 of phenomena. 



What bearing have these results relating to castration and trans- 

 plantation on the theory of sexual selection? Granting, of course, that 

 selection takes the materials as it finds them, there may still be restric- 

 tions imposed on the theory by the kind of material offered. For 

 instance, the development of the plimiage of the cock is independent 

 of the condition of his testes. Hence, if the female selected the more 

 vigorous male, she would not necessarily obtain one more ornate than 

 his less vigorous rivals. If the taste of the hen has built up the plumage 

 of the cock, it has been carried out then independently of the vigor 

 resulting from the greater activity of the testis. In a word, the more 

 vigorous male is not necessarily the most highly colored one. Darwin 

 concedes that these two conditions, high color and vigor, must go 

 together to insure success, or at least that the most vigorous and there- 

 fore the most highly colored male will have more offspring. Wallace's 

 contention that the greater vigor of the male accounts for his greater 

 development of plumage gets scant support from the facts of castra- 

 tion. One might rather contend that the female must be more vigorous, 

 since she is obliged to suppress plumage that is allowed to run riot in 

 the male. 



Wallace's argument in favor of natural selection holding down the 

 plumage in the female as a protection to her while nesting might 

 appear to fit the facts better were it not that the quest for an explana- 

 tion of the male's plumage is thereby abandoned. It should not be 

 forgotten in this connection that the nest is generally only partly 

 concealed, that bright color at rest need not be conspicuous, and that 

 the male, exposed as he is through a considerable part of the year, still 

 manages to maintain himself in about equal numbers with the female. 

 Suppose, however, for the sake of argument, that natural selection has 

 kept under the full possibilities of the female. The modus operandi 

 would be competition between the least adorned females, suppression 

 being brought about by the activity of the ovary; while the male is 

 left therefore to exhibit the full possibilities of the genetic complex of 



