INTERSEXUALITY 393 



gonads of the only cock-feathered bird mentioned above, 

 whereas they were present in all the hen-feathered intersexual 

 hens. 



If we go through all the cases of intersexuality in birds as 

 related above, it is clear that only in some of them can a 

 correspondence between the sex characters and the gonad be 

 detected, whereas in others such a correspondence is absent. 

 But, in accepting the hormonic theory of intersexuality, should 

 we expect that in every case of intersexuality conditioned by 

 some pathological disturbance there will be a correspondence 

 as required by the theory? Should we expect such a corre- 

 spondence, when we see that even in experimental feminization 

 and masculinization or in experimental hermaphroditism it 

 is not always possible to predict the same positive result ? 

 Notwithstanding the fact that many things the authors 

 observed do not wholly agree with the hormonic theory of 

 intersexuality, I think that these observations give support 

 to this theory. It may be, however, that the hormonic 

 factor is sometimes counteracted temporarily by somatic 

 factors. 



There might be also cases in birds where some other endo- 

 crine gland is the primary cause of intersexuality. Berner 

 (1923) has described a hen which exhibited a male-Hke large 

 erect comb and spurs; the plumage was a female one, but eggs 

 were never laid. There was a big suprarenal tumour ; the ovary 

 was small, but contained ova surrounded by groups of lutein 

 cells. 



Considerable support to the hormonic theory of inter- 

 sexuality is given by the experiments of Morgan (1919-20) on 

 the Sebright and Campine cocks. In the Sebright race the 

 cock is normally hen-feathered, but becomes cock-feathered 

 when castrated. It is the same with the Campines, where 

 there are in some stocks only hen-feathered males, in other 

 stocks both hen-feathered and cock-feathered males. It is 

 evident that the intersexual condition being the rule in these 

 races is caused by the hormonic activity of the testicle. Accord- 

 ing to Morgan and Boring luteal cells are to be found in the 

 testicle of the Sebright cock; similar cells were found in the 

 testicle of the hen-feathered Campine. Morgan ascribes to 

 these cells the hormonic activity of the testicle which leads to 

 hen-feathering. Doubt has been thrown on this view by 



