INTERSEXUALITY 397 



the adrenals, if really conditioning maleness, can have 

 this influence only by the intermediation of the sex gland, 

 the latter forming some kind of a junction point between the 

 sex characters and other endocrine glands. Blair Bell's case 

 shows this very clearly. The question of such an intermediation 

 of the sex gland has been experimentally studied in birds. 

 Torrey and Horning (1922) showed that hen-feathering can be 

 induced in cocks by feeding with thyroid. Further, these 

 observers stated that the sex gland is a necessary factor in this 

 result, since no castrated male assumed female plumage when 

 fed with thyroid. Experiments in which normal and castrated 

 females were fed with thyroid also gave negative results. The 

 experiments of Torrey and Horning lead to the conclusion which 

 we have always supported, that feminization and masculiniza- 

 tion are the sex specific effects of the sex glands, and that in so 

 far as any other endocrine gland influences the sex characters 

 this is done by the intermediation of the sex gland. The action 

 of the thyroid on fowls has been recently studied also by 

 B. M. Zawadowsky (1923). He claims that by thyroid feeding a 

 premature moulting can be caused; the new feathers are poor 

 in pigment. There was in one cockerel an underdevelopment 

 of the head apparel and an almost complete absence of spurs ; 

 no sexual instincts were present. It is difficult to say how 

 far the results of B. M. Zawadowsky corroborate those of 

 Torrey and Horning. Crew and Huxley (1923 a) repeated the 

 experiment of Torrey and Horning on twelve male and female 

 chicks; the animals developed in the usual manner. The most 

 probable explanation is that the positive or negative result 

 depends on the quantity of thyroid hormones introduced. 



There are, however, facts which seem at first sight to be 

 contrary to our theory, such as the cases of lateral inter- 

 sexuality observed both in mammals and in birds, but especially 

 in the latter. These cases will be discussed in the last section 

 of this chapter. 



4. Amphibians. 



Intersexuality in frogs has repeatedly been the subject of 

 observation and experiment. Intersexual frogs have been 

 described by various authors, and the condition has been 

 induced under different experimental conditions. The whole 

 question as to the bearing of the internal secretion of the sex 



