GONADS AS CONTROLLERS OF CHARACTERISTICS 149 



to reveal the slightest interest displayed by either spayed females 

 or castrated males. ^- 



B. Masculinized females 



In order to observe better the reactions of the masculinized 

 females, these were placed alone in cages for a day or so before 

 subjecting them to the experiment. The various rats were then 

 put into the cage and the reactions of the masculinized female 

 noted. 



Practically any two strange white rats placed together in the 

 same cage immediately show interest in each other, and whether 

 they are two normal males, two females, or male and female they 

 almost at once begin to nose around the external genitals of each 

 other, and many times if they are both males a fight begins. 

 These reactions are general for practically all rats when placed 

 together. But in case the two are a normal male and a female 

 in heat, the act of copulation begins immediately and, though 

 of very short duration, may be repeated a great number of 

 times. 1^ But in all the writer's experience among the rats of 

 the colony used (amounting to several hundred) he has never 

 observed a normal female attempt to imitate the male in the act 

 of copulation. One of the most, perhaps the most characteristic 

 feature of the whole process of copulation in regard to the male, 

 is that after each attempt almost invariably the male assumes 

 immediately^ a position that allows him to lick the copulatory 

 organ before the next repetition. 



It is a very interesting fact that the masculinized female would 

 attempt to imitate the male in the act of copulation in an ab- 

 solutely typical set of reactions. Of course, no male copulatory 



1- The spayed and castrated rats of cage 37 were at this time over six-months 

 old and had been operated on at the age of about thirty days. These rats nor- 

 mally would have been sexually mature. 



^' The males are not especially keen discriminators, for if a female in heat is 

 placed in the cage with several males the excitement is very great and repeatedly 

 results in one male attempting to copulate with another. This attempt is also 

 often made if a male is placed in a cage with a single male, especially so if a female 

 in heat has just been removed from the cage of the male. 



