SEXUAL BEHAVIOR OF ALBINO RAT 131 



In a similar manner Havelock Ellis 8 describes the arousal 

 of sexual activities through particular kinds of exteroceptive 

 stimulation. According to him: 



External stimuli act at every stage, arousing or heightening the proc- 

 ess of tumescence, and in normal human beings it may be said that the 

 process is never completed without the aid of such stimuli, either 



active or in imagination The chief stimuli which influence 



tumescence aud thus direct choice come chiefly indeed, exclusively 

 through the four senses of touch, smell, hearing, and sight. All the 

 phenomena of sexual selection, so far as they are based externally, act 

 through these four senses. 



He evaluates the four senses with respect to their effectiveness 

 in arousing sexual responses as follows: "Of the four senses 

 touch is the more primitive, and it may be said to be the most im- 

 portant, 41 though it is usually the last to make its appeal felt. 

 Smell, which occupies the chief place among many animals,* is of 

 comparatively less importance, though of considerable interest, 

 in man; it is only less intimate and final than touch." 5 



Such statements, although lacking in concrete detail, are of 

 interest in this connection because they serve to suggest a feas- 

 ible point of attack for the study of the activation of the copu- 

 latory act. Given an inexperienced male rat which has 'reached 

 the stage of physiological development denoting copulatory 

 ability, one needs only to supply the adequate stimulus to evoke 

 the copulatory act. Under this condition, a study of the process 

 of activation consists primarily in the analysis and definition of 

 the stimuli acting together with their mediation through the 

 agency of the receptors. 



Experiments along these lines, so far as they have been suc- 

 cessful, indicate that with further extension of experimentation 



* Psychology of Sex, Vol. 4, p. 1-2 incl. 



4 Italics mine. 



s Although these quotations are taken from his studies dealing primarily 

 with the sexual life of man, they have in them points of general applicability 

 to the sexual behavior of the lower animals as well, for the fundaments of his 

 sexual theory as a whole are taken from data of comparative physiology and 

 psychology. 



