SEXUAL BEHAVIOR OF ALBINO RAT 105 



Withdrawal, as a rule, is made immediately upon the consum- 

 mation of the orgasm, but in the case of males copulating for a 

 somewhat prolonged period of time, there occurs now and then 

 an instance of failure or retarded withdrawal after cessation of 

 piston movements. Prolongations of from one to five seconds 

 have been observed. In these cases the withdrawal is effected 

 by the male alone, with the elimination of the backward lunge, 

 or by the female's jumping forward and slipping from the relaxed 

 clasp of the male. One female on the occasion of tardy with- 

 drawal invariably squealed sharply and turned savagely on the 

 male, striking at his head with her fore-paws or viciously biting 

 at his face and shoulders. 



2. Sexual behavior of the young rat 



The sexual behavior of approximately fifty young males and 

 three young females was observed in this study under ordinary 

 cage and experimentally controlled conditions. Before consid- 

 ering the data gathered in these observations the methods used 

 in systematically sampling the behavior of certain young males 

 and females will be described. 



Two series of systematic observations on young rats were 

 made during their prepuberal development and for a short tune 

 thereafter. These series differ somewhat in type and serve to 

 supplement each other. In the first series 15 males and 3 females 

 were observed from the age of thirty days to the age of somatic 

 maturity. The group consisted of the following animals: 6 

 normal males; 3 normal females; 2 blind, 4 anosmic, and 3 cas- 

 trated males. 



The fifteen males were confined in a large cage (18 by 20 by 

 30 inches) while not in their individual observation cages. The 

 females were kept with a group of from two to four females of 

 the same age in a smaller cage (10 by 16 by 14 inches). Daily 

 all were isolated in individual cages for a period of from four to 

 six hours prior to the time observations were made. Between the 

 hours of 5.00 and 8.00 p.m., when the animals are normally very 

 active, a female non-receptive 1 as a rule, but receptive when 



1 The term non-receptive is used to describe females that would not copulate 

 females not in heat. 



