SEX AND SEXUAL CHARACTERS 461 



characters proper to the sex. Thus Mr. Shattock tells me 

 that in the cow the pelvis is larger than in the bull, and that 

 in a cow which was spayed at an early age the enlargement 

 of the pelvis did not take place. 



We are not justified then in assuming that the develop- 

 ment of male characters which occurs occasionally in females 

 is due merely to the suppression of the ovarian function. It 

 is true that in several cases dissection has shown that the 

 ovary was reduced to a small vestige. Two such cases are 

 described by Shattock and Seligmann (2) : one that of a gold 

 pheasant, the other of a wild duck. But on the other hand,, 

 male-plumaged hens are not always sterile : Homelie records 

 a case of a cock-feathered hen which continued to lay eggs 

 and hatch chickens, and at the fourth moult became hen- 

 feathered again ; and Shattock and Seligmann had a male- 

 feathered duck which laid eggs. It has been found that in 

 Passerine birds male-plumaged hens occur, and that the 

 condition is not associated with sterility or atrophy of the 

 ovary, dissection having shown that the ovary was large and 

 functional. It is evident that the condition is not the con- 

 stant result of old age or sterility or removal of the ovaries, 

 but is an abnormality occurring in a few individuals. Two 

 explanations of this abnormality are possible : we may suppose 

 that in these cases a mutation has occurred which makes the 

 male characters develop without the stimulus of the hormone 

 from the gonad, or we may suppose that the individuals are 

 really hermaphrodite — that testicular tissue is really present, 

 and produces the hormone or internal secretion which causes 

 the development of the external male characters. With regard 

 to the first hypothesis, we have good reason to believe that 

 such a variation has frequently occurred both in nature and 

 under domestication, as in the case of the antlers of the 

 female reindeer and the large comb and wattles and even 

 spurs in the hens of many breeds of fowl. The second view 

 is that put forward by Shattock and Seligmann — namely, that 

 the female birds which assume the male plumage are really 

 hermaphrodite : either the ovary being bisexual, or the male 

 element being displaced and included within a neighbouring 

 viscus, such as the adrenal or the kidney — and this view de- 

 rives support from the fact that females in such a condition 

 often exhibit male sexual instincts. For all we know, the sterile 



