36 INTERNAL SECRETIONS 



mammal. These external factors seem to be very uniform in 

 the latter, and olfactory stimuli play an important part. 

 Steinach records an experiment in which he smeared the labia 

 of a female rat with a mixture of cod liver oil and paraffin, 

 with the result that this female was not followed, and coitus 

 was not attempted with her by a bhnd male until the labia 

 were cleaned with soap, when the male once more showed 

 sexual excitement in her presence. On the other hand the 

 sexual reflexes in man are put in action by many different 

 stimuli. It seems that in man any external stimulus may excite 

 the sexual reflexes. This is due to the high psychical de- 

 velopment of man. Sexual fetishism finds its roots therein, 

 being some kind of a "conditional reflex" in the sense of 

 Pavlov. So it is not difficult to understand that sexual 

 activity may persist some time in man after postpuberal 

 castration, and a priori one would expect to find sexual activity 

 even in the postpuberally castrated man more often and more 

 markedly than actually is the case. Persistence of some 

 signs of the sexual activity which diminish very slowly after 

 postpuberal castration is by no means incompatible with the 

 contention that the erotization of the nervous system (Steinach, 

 1910) depends upon the sexual glands. 



What we said about the influence of the sexual glands on the 

 development and the maintenance of the sexual reflexes in 

 animals and in man is also true for the heat of mammals so 

 far as it concerns changes in the psycho-sexual behaviour 

 during this period. In experiments with female hares Bucura 

 (1913, p. 22) show^ed that after castration heat never occurred. 

 In experiments made with normal male rabbits and females 

 castrated prepuberally Lacassagne (1913, p. 218) never saw 

 signs of heat. As already mentioned, Marshall could prevent 

 heat in the male hedgehog by removal of the testicles. 



C. THE RESULTS OF CASTRATION IN BIRDS. 



Observations. 

 Castration has been performed for a long while on the cock 

 for economic reasons. Systematic experiments on the cock 

 have been made by Sellheim, Foges, Poll and others. But 

 nevertheless there has never been complete unanimity con- 

 cerning the results of castration. As Goodale (1916, p. 27) 



