SEXUAL BEHAVIOR OF ALBINO RAT 99 



A very elaborate study of the sexual behavior of monkeys and 

 baboons was made by Hamilton ('14). The animals were given 

 far more freedom in their place of confinement than is customary 

 in such studies. Thus reactions closely approximating those 

 found in the natural habitat were observed. Some of the out- 

 standing features of this study are: the great amount of sexual 

 intercourse performed by the males, homosexual tendencies of 

 both males and females, and the use of homosexual behavior on 

 the part of the weaker individuals to divert the attacks of larger 

 males in their attempts at copulation. Under normal conditions 

 of life, the young male, the author believes, does not form habits 

 of masturbation. 



Motani ('16) describes the dominating behavior of a male 

 chimpanzee directed toward its cohabitant. When intercourse 

 was desired the male hit the floor of the cage with his hand, 

 whereupon the female approached and assumed the copulatory 

 position before him. Copulation during pregnancy was frequent. 



Studies dealing with the reproductive glands as the chief or- 

 gans exerting a regulatory influence over sexual phenomena are 

 now quite numerous. Although the data of these reports are 

 to some degree relevant to those to be reported in this paper, 

 they can be more advantageously considered in connection with 

 the subsequent study which deals with the internal factors under- 

 lying sexual behavior. Such literature will, therefore, be reviewed 

 at a later time. 



3. Technique General 



The rats were confined in a uniformly heated room. An 

 extra allowance of whole milk was given to the mothers through- 

 out the period of lactation in order to assure favorable condi- 

 tions for normal development in the suckling young. Approxi- 

 mately half of the litters were weaned when twenty-one days of 

 age; the other half, at the age of twenty-five days. Although 

 the latter gained weight more rapidly, during the subsequent 

 five or ten days, than those weaned at twenty-one days, this 

 difference in rate of gain was only temporary and so small that 

 it was entirely concealed by the individual variations in rate of 



