458 SCIENCE PROGRESS 



Prof. Bateson and Mr. Doncaster assert that castration of the 

 male in Vertebrates may prevent the appearance of the male 

 characters, but does not cause the appearance of characters 

 proper to the female ; while, on the other hand, removal or 

 atrophy of the ovaries may bring about the development of 

 characters normal in the male. They consider that this proves that 

 the female possesses the male sex in a latent condition, but that 

 the female sex is entirely wanting in the male. Thus there are 

 two questions to be considered : firstly, whether their statement 

 is in accordance with the facts at present known, and secondly, 

 what is the relation of the secondary sexual characters to sex ? 

 It is evident that the above statement refers to secondary sexual 

 characters, such as the antlers of stags, or the male plumage 

 of birds ; whereas the only primary and essential difference 

 between the sexes is that the male produces spermatozoa, and 

 the female produces ova. It has long been known that the 

 normal development of secondary characters in male Vertebrates 

 depends on the normal condition and functional activity of the 

 testes, and that after castration these characters fail more or less 

 completely to develop. It has recently been discovered that 

 the connection between the primary organ and the secondary 

 characters is chemical ; that the normal development of the 

 secondary character requires the stimulus of a chemical secretion 

 or hormone present in the blood, and derived from the gonad. 



Of the various experimental investigations which have 

 demonstrated this important fact in different Vertebrates, it will 

 be sufficient to mention the following. In 1905 Nussbaum (10) 

 first castrated male specimens of the frog, Rana Jusca, and found 

 that the " brunstorgane," or nuptial organs — that is to say, 

 the swelling on the inner side of the fore-foot and the enlarge- 

 ment of the muscles of the fore-leg, which are present in the 

 breeding-season— failed to develop. He then inserted in the 

 dorsal lymph-sac of a castrated frog pieces of the testis of 

 another frog, and found that the nuptial organs developed to 

 the same degree as in the entire male. The pieces of testis 

 introduced were absorbed — no vascular or nervous connections 

 were formed ; therefore the result must have been due to 

 chemical influence — some part of the substance absorbed from 

 the testis must have had the power to stimulate the tissues 

 of the fore-leg and cause the enlargement of the integument on 

 the fore-foot to develop. It had been proved that the develop- 



