RESULTS OF CASTRATION 63 



as we have seen, for birds. From the experiments of Steinach 

 on rats, and those of Pezard and Goodale on cocks, it seems 

 probable that such an inhibitory action on the part of the 

 sexual glands exists. We shall discuss these experiments more 

 fully in Chapter VI. 



Smith explains his observations in a wholly different 

 manner. He begins by pointing out that in the female, as in 

 the male, there is sometimes an hermaphrodite sexual gland 

 with almost fully developed ova and spermatozoa. Smith 

 thinks that these were males which were first castrated by 

 parasites, and that afterwards an hermaphrodite gland devel- 

 oped. We have seen that female sexual characters may be 

 present in the castrated male also when no hermaphrodite 

 gland is present; it follows from this that the female somatic 

 characters in the modified male are not caused by the newly 

 formed ovary. Smith suggested that there is another factor, 

 a sexual formative substance which causes the development 

 both of the somatic sexual characters and the sexual glands. 

 According to him this formative substance may be thought 

 of as a product of the general metaboHsm ; under the influence 

 of the parasite the formative substance is changed, and in this 

 way an atrophy of the sexual glands and a change in the 

 sexual characters are caused. Further, Smith assumes that 

 there is in every male a potential formative substance in 

 relation to both sexes, the female one being latent; in the 

 female sex the female substance only would be present. Now 

 he assumes that in the male castrated by the parasite the male 

 substance only is destroyed, and so the female substance 

 inverts the animal to the female sex. 



I do not think that Smith's hypothesis is justified in all its 

 details, and I do not think that it is sufficiently supported by 

 what Smith observed. But it is interesting to note that in 

 this hypothesis we have a clear foreshadowing as long ago 

 as 1906 of a later and somewhat similar theory based on a 

 remarkable body of evidence, and already tentatively accepted 

 by many. For the experiments of Goldschmidt on moths 

 make it probable that there is indeed a sex specific formative 

 substance controlling both somatic sexual characters and 

 generative cells, and that in the same individual the male and 

 female sex-specific substance may be present, one of them being 

 latent, and that a turning over to the other sex may be caused 



