SEXUAL BEHAVIOR OF ALBINO RAT 143 



about by tactual and thermal stimulation of the penis within 

 the walls of the vagina. Just how these stimuli produce their 

 effects is a problem for future analysis. 



Cutaneous and deep sensibility have not been subjected to 

 experimental control in this study. Technical difficulties en- 

 countered in the control of their individual receptors are ex- 

 ceedingly great and may prove to be unsurmountable because 

 of their inaccessability and the diffuse distribution throughout 

 the body. The use of drugs for the dissociation of sensibility 

 for particular regions of the body is unsatisfactory because of 

 the difficulty of controlling and limiting the range of drug influ- 

 ence on neighboring tissues. Nerve section followed by gross 

 dissection and histological examination at autopsy to determine 

 the range of distribution of destroyed nerves may be a feasible 

 method of dissociating the cutaneous from the deep sensibility, 

 but this method of approach will involve refinement of technique 

 beyond that now available. 



Further definition of the adequate stimulus has been attained 

 through observation of the behavior of young males and adult 

 females at the tune of the initial copulation of the former. This 

 has also been accomplished by the use of artificial patterns of 

 stimulation to evoke the sexual act. 



2. Artificial reproduction of pattern of stimulation 



While young males were being tested to determine the earliest 

 age at which copulatory ability appears it was discovered that 

 the amount of sexual excitement aroused in the young male 

 depended to a marked degree on the excitability and responsive- 

 ness of the receptive female. Females that were very sensitive 

 and move quickly upon being touched by the young male were, 

 invariably, most effective in arousing sexual aggression on the 

 part of the male. On the other hand, those that were unrespon- 

 sive to the light tactual stimuli of the male, sniffing and nosing 

 the ano- vaginal zone, but responded only to vigorous treatment, 

 such as the more aggressive adults were accustomed to administer, 

 seldom aroused strong and prolonged sexual excitement in the 

 inexperienced male. This observation is true for adult males, 



