46o INTERNAL SECRETIONS 



generative cells, and they still persist in the embryonic 

 soma as long as sexual differentiation has not yet take 

 place. Rudiments of these parts persist also in the sexually 

 differentiated individuals. One may assume, therefore, that 

 the asexual embryonic soma in mammals and birds recapitu- 

 lates a phylogenetic phase in which sexual differentiation related 

 only to the generative cells. The rudimentary organs which 

 seem to be signs of an intersexual soma (the appendix 

 vesiculosa, the appendix epididymidis, the ductus longitudinalis 

 of the epoophoron) may be rudiments of an excretory apparatus 

 common to both sexes, like the ductuli transversi of the 

 epoophoron and paroophoron, and the ductuli transversi of the 

 epididymis and paradidymis [Fig. 137). 



(2) With reference to the second group of facts mentioned 

 above we know that the manifestation of characters of the 

 opposite sex may be brought about by a change in the dynamics 

 of the hormonic apparatus. In some cases such as the cock- 

 feathering of old hens, the appearance of characters of the 

 opposite sex may be regarded as due to a suppression of 

 hormone-production, which previously inhibited the develop- 

 ment of the characters of the asexual type. No special genetic 

 factors seem to be necessary to account for these facts. 



(3) Let us now consider the third group of observations 

 relating to the transmission of female characters by the father 

 and of male characters by the mother. This phenomenon can 

 be easily explained if we assume that the parent transmits to its 

 offspring the characters of the asexual type, i.e., the capacity to 

 react to sexual hormones in a manner characteristic of a given 

 species. The parent always transmits the capacity to react both 

 in a male and in a female manner. In crossing experiments the 

 male generative cell transmits characters of the asexual soma 

 of the strain of the father, and the capacity to react to female 

 sexual hormones in a manner characteristic of the female of the 

 father's strain is thereby inherited. On the other hand, the 

 female generative cell in a crossing experiment transmits the 

 characters of the asexual soma of the mother's strain, and the 

 capacity to react to male sexual hormones in a manner charac- 

 teristic of the jnale of the mother's strain is thereby inherited. 

 It depends upon the sex specific hormones of the offspring 

 whether the reaction of its soma will be a male or a female one. 

 I find my view, as expressed in the first edition of this book. 



