INTERSEXUALITY 391 



plumage. Pezard stated that the ovary and the oviduct were 

 much reduced. Interstitial cells and highly atretic follicles 

 were present. The adrenals were normal. Pezard considers 

 this case as conditioned by a deficiency of ovarian hormonic 

 activity, the ovary having been reduced below the minimal 

 quantity necessary for feminization. A similar case was 

 observed by Murisier (quoted from Pezard, 1922 a). 



There is no intersexuality in the above-mentioned cases, 

 as said above, but only assumption of the neutral form. One 

 can only speak of intersexuality in fowls, if there is, in addition 

 to an assumption of male plumage, an increase of head apparel 

 or change of sexual instincts. Similar cases of intersexuality 

 seem to be not very uncommon in fowls. Several authors 

 have described such cases. Boring and Pearl (1918) have 

 published an extensive study of this question. These authors 

 have also carefully examined how far there is a correspondence 

 between the sex characters and the sex glands in herma- 

 phrodite birds. I shall describe these cases, since they afford 

 the best examples available of different forms of intersexuality 

 in birds. Eleven birds were examined. Two guinea chicken 

 hybrids were entirely male in external characters, but in- 

 different as to sexual instincts. The testicle was not normal; 

 it was probably an undifferentiated gonad, no tubules being 

 present. Interstitial cells and luteal cells were also absent. 

 A hen treading other hens was quite normal as to the gonad. 

 Three hermaphrodite birds revealed during their life history a 

 marked change from femaleness to maleness, in respect both 

 of somatic sex characters and of sex behaviour. They fought 

 both males and females, and crowed and made attempts to 

 copulate, though one of these hens formerly even laid eggs. 

 In two of them the comb was well developed. The carriage 

 was male-like, and the body shape was similarly male in two 

 cases. These two birds assumed also some signs of male 

 plumage. All these hermaphrodite birds had ovariotestes. 

 In one case spermatozoa were present, in another case sper- 

 matids ; in the third case only spermatogonia and spermatocytes. 

 Interstitial cells and luteal cells were present in the ovarian 

 part in different degrees. The authors consider these cases as 

 females changing to males in respect of the gonad also. Further, 

 they observed five birds with female plumage, with a more or 

 less developed comb, wattles and spurs, and with a more or less 



