412 INTERNAL SECRETIONS 



already indicated in a foregoing section of this chapter, 

 Goldschmidt has built up the theory of intersexuality in the 

 moth on a similar basis. Such a theory is also held by 

 Zawadowsky in view of his observations on birds related above 

 (see p. 312). It may be remembered that he observed masculi- 

 nization in hens under the influence of a regenerating ovary. 

 Like Steinach and ourselves, Zawadowsky (1923) is inclined to 

 explain the change of sex as due to the action of heterosexual 

 hormones which previously could not influence the sex 

 characters on account of these hormones being dominated by 

 those of the other sex. Also the experiments of Meisenheimer 

 (1912) on the frog show that the ovary possibly produces 

 some hormones which are similar to those of the testis. 



Now a second important question arises : what factors can 

 produce a quantitative disturbance of the hormonic activity of 

 the sex gland in such a way as to influence the sexual characters ? 

 It is well known that tumours of the adrenals may have this 

 effect. But what do we know about the mechanism of this 

 influence? I have already pointed out that the hyperneph- 

 roma which has a masculinizing influence probably does not 

 act directly through male sexual hormones upon the soma, 

 but more likely influences the sex gland producing some 

 disturbance of its hormonic activity. It may be remembered 

 in this connection that, according to Matthias, a hyperneph- 

 roma may cause not only masculinization of a female individual, 

 but also feminization of a male one. 



The different problems touched on in this section are by no 

 means solved. What we need for the moment are working 

 hypotheses to guide us in further experimental research in 

 this field. 



