462 SCIENCE PROGRESS 



or even the atrophied ovary in such cases may produce the 

 male hormone. 



It may be urged, however, that whatever may be the 

 explanation of the occasional assumption of male characters by 

 the female, a corresponding development of female characters 

 in the male does not occur. There are several reasons why 

 the corresponding change should be less conspicuous in the 

 male. In the first place, the female characters in Vertebrates 

 are for the most part negative — that is to say, the female 

 adult does not develop new characters, but remains in the 

 same condition as the immature young ; and thus the assump- 

 tion of the female character would be the same thing as the 

 absence of the male character. Another difference is that 

 in the male there is not a definite limit to the functional 

 activity of the gonad — it may continue (though with diminished 

 vigour) to extreme old age. Thus, if in a particular individual 

 there was a female tendency present, it might not show itself 

 because held in check by the functional male gonad. Where, 

 however, positive female characters do exist, we find evidence 

 of their occasional development in the male. The best example 

 is afforded by the mammary glands. The fact that these 

 are normally present in a rudimentary condition in male 

 mammals is to my mind sufficient to disprove the theory 

 of the Mendelians ; for the suggestion of Darwin that they 

 were originally functional in both sexes seems to me contrary 

 to all probability. Many cases are on record of the mammary 

 glands becoming functional in males, both in the human species 

 and in other mammals ; and, as in corresponding cases in 

 females, the abnormal development is not common to all 

 castrated individuals, but occurs exceptionally in both entire 

 and castrated males. The wide pelvis is another positive 

 female character in the human species, and in others — such 

 as the cow — where a single large young is produced at birth ; 

 but there is little trustworthy evidence of the development 

 of this character in males. It has been sometimes assumed 

 that this last character is developed in castrated human males ; 

 but the evidence is not definite, as hitherto little attention 

 has been paid to the distinction between the absence of 

 male and presence of female characters after castration. In 

 some cases it is difficult to decide which of these two descrip- 

 tions applies to an abnormality. For instance, Shattock and 



