336 INTERNAL SECRETIONS 



in the seminal vesicles. According to Tarchanoff a distention 

 of the walls of the vesicles by the fluid content produces a 

 mechanical irritation of the nerve-endings, and he suggests 

 further that their excitation may be increased by the sper- 

 matozoa hitting against the walls of the vesicles. Steinach was 

 able to show that Tarchanoff' s assumptions were not justified. 

 In frogs which had already been clasping for several days the 

 seminal vesicles were found to be empty, for the filling of the 

 vesicles takes place only after the clasp begins. It is clear 

 that the sexual instincts of the frog during "heat" and the 

 clasp reflex cannot be caused in the manner supposed by 

 Tarchanoff. Further, Steinach showed experimentally that 

 spontaneous clasping or clasping after stimulation is still 

 possible when the seminal vesicles have been extirpated. In 

 animals from which the seminal vesicles have been removed, 

 however, the clasp continues for only about ten days. But 

 according to Steinach, this is to be explained by the fact that 

 in extirpating the seminal vesicles the ureters are severed, and 

 the urine flows into the abdominal cavity. The experimental 

 animals show many pathological symptoms and die about 

 twenty days after the operation. Nussbaum's experiments 

 gave further support to Steinach's conclusions. 



It is clear that in the frog the seminal vesicles have nothing 

 to do with the erotization of the central nervous system. 

 This effect is due only to the testicle. 



2. Experiments on Mammals. 



Steinach removed both seminal vesicles from rats ten to 

 eleven months old. The experimental animals about ten days 

 after the operation displayed a marked sexual behaviour, just 

 like normal ones. But breeding experiments performed by 

 Steinach showed that by removing the seminal vesicles the 

 fertility may be much diminished. Only a very small percentage 

 of the females with which the operated males copulated 

 became pregnant; the number of young in the litter was 

 about half that of the normal. One might object that the 

 diminished fertility was possibly caused by obstruction of 

 the vas deferens, but such an objection is not justified, since 

 each male was able to impregnate at least once. 



Similar observations were made by Camus and Gley (quoted 

 from Camus et Gley, 1899) on the guinea pig, the fertiHty of 



