THE EFFECTS OF CASTRATION 145 



OPERATIONS ON AMPHIBIA 



The male triton develops each year a peculiar fin or 

 comb on the back and tail. Bresca has found that 

 after castration the comb does not develop. If present 

 at the time of castration, the comb is arrested, but 

 only after several months. Certain color marks pe- 

 culiar to the male are not lost after castration. If the 

 comb is removed in normal males, it regenerates, but 

 less perfectly in castrated males. If a piece of the 

 dorsal fin of the female is transplanted to a normal male 

 in normal position, it may later produce the comb under 

 the influence of the testes. 



In the frog there appears at the breeding season a 

 thickening of the thumb. Castrated males do not 

 produce this thickening. 



If it is present in a male at the time of castration it 

 is thrown off, according to Nussbaum, but according to 

 Smith and Shuster its further progress only is arrested. 

 According to Nussbaum and Meisenheimer injection 

 of pieces of testes beneath the skin of a castrated male 

 cause the thumb development to take place, or to 

 continue, but Smith and Shuster question this con- 

 clusion. 



Such are the remarkable relations that these experi- 

 ments have brought to light. How, we may ask, do 

 the sex glands produce their effect, in the one case to 

 add something, in the other to suppress something? 



It has often been suggested these glands produce 

 their effects through the nervous system by means of 

 the nerves to or from the reproductive organs. This 

 has been disproved in several cases by cutting the 



