52 



INTERNAL SECRETIONS 



of Rana temporaria in the first days of January, whereas the 

 control animals were dealt with by a simple laparotomy, the 

 testicles remaining intact. Early in March the control animals 

 began to embrace spontaneousl3\ On the other hand, not 

 one of the castrated frogs embraced spontaneously. Harms 

 (1914, pp. 175, 176) stated that the castrated male makes the 

 oestral sound only alter artificial irritation of the skin ; then a 

 dull, hoarse noise can be heard. 









V-^ 



. '/•' 



% 



Fig. 35. — Pad of male Rana temporaria in July, after period of heat, x 80. — 

 Prepar. of Wagner; photo, of KuU. 



A dependence of the oestral characteristics on the sexual 

 glands has been observed also in other Amphibia. Bresca 

 (1910) has shown that the atroph}^ of the nuptial apparel of 

 the triton can be accelerated if both testicles are removed. 

 Recently Avon (1921, a, b) has investigated this question in a 

 more detailed manner. He performed bilateral castration 

 just at the beginning of the breeding season; the development 

 of the nuptial apparel was stopped, and it atrophied rapidly. 

 If castration is done when the nuptial apparel is alread}^ fully 



