38 THE GENETIC AND THE OPERATIVE EVIDENCE 



authors say, were "evidently undeveloped females. They have infantile 

 oviducts and embryonic ovaries." It should be added that there was a 

 tumor more than twice the size of the ovary attached to or part of the 

 ovary. If the ovary itself was affected by the tumor, or the tumor was 

 a part of the ovary, the slightly unusual condition of the birds might 

 be accounted for. Of the other 3 birds, 2 are also suspected to have 

 ovarian tumors,, while in the third bird streaks of a secretion which 

 resembles the substance of the tumor of the other two were found. 

 The change towards male plumage in these 5 birds is probably due 

 either to the incomplete development of ovary or to the effect of the 

 tumor on the ovary. Although luteal cells are described as present, it 

 seems probable that their total number might be less than in a normal 

 bird, and hence their insufficient secretion would fail to suppress the 

 development of male plumage. From this point of view these birds 

 are no more hermaphrodites than is a hen with her ovary taken out. 



The remaining Holland birds were entirely different. On the left 

 side there was an ovary in an inactive condition ; on the right side there 

 was a testis, producing spermatozoa. Sections of the testis show 

 that it is normal, consisting of a mass of tubules with very little con- 

 nective tissue between them. In both ovary and testis there are "a 

 few nests of luteal cells near the surface. The ovary contains eggs, but 

 is abnormal to some extent." The authors state: 



"In external appearance it is more like a male than the others, which fact 

 correlates well with the active condition of the testis and inactive diseased 

 ovary, with only one corpus luteum scar. The interstitial cells can scarcely 

 be held accovintable for the male secondary sex characters, as the only ones 

 in an active secreting condition are a few in the ovary." 



It is not quite clear what is meant in this quotation by the statement 

 that the interstitial cells can scarcely be held accountable for the male 

 secondary characters unless to suggest that they cause the development 

 of these characters in the male, as they are supposed to do in mammals — 

 a view that the authors do not seem at other times to hold. 



Another hermaphrodite (Atwood's black) had an infantile oviduct 

 and an ovotestis. A second bird, too, had an ovotestis — mostly 

 testis— as well as a rather large oviduct. Collections of luteal cells 

 are described between the tubules of the testicular portion. If, as 

 suggested by the Sebright cases, these cells tend to suppress the female 

 plumage, their presence here in excess might at least be made to account 

 for the female part of the plumage of this bird. Comparing the last 

 two birds (that showed active sex-behavior as males) with the best 

 of the Holland birds. Boring and Pearl point out that the active sex 

 behavior of the two former can not be due to "interstitial cells that are 

 absent in these but present to a slight extent in the former." They 

 then add " . . . . though the differences can not be laid to the lutear cells, 



