210 TABOO AND GENETICS 



thrown a great deal of light upon the nature 

 of the individual sex life. 



There are certain modifications of the erotic 

 life which are explicable only when we recollect 

 that under environmental influences situations 

 which originally did not call up an emotional 

 response come later to do so. This fact, which 

 was first noted by Setchenov, was experimentally 

 demonstrated by Pavlov and his students. (7). 

 They found that when some irrelevant stimulus, 

 such as a musical tone or a piece of coloured 

 paper was presented to a dog simultaneously 

 with its food for a sufficiently long period, the 

 presentation of the tone or paper alone finally 

 caused the same flow of saliva that the food had 

 originally evoked. The irrelevant stimulus was 

 named a food sign, and the involuntary motor 

 response of salivary secretion was called a 

 conditioned reflex to differentiate it from the 

 similar response to the biologically adequate 

 stimulus of food, which was termed an uncon- 

 ditioned reflex. 



" The significance of the conditioned reflex 

 is simply this, that an associated stimulus 

 brings about a reaction ; and this associated 

 stimulus may be from any receptor organ of 

 the body ; and it may be formed of course 

 not merely in the laboratory by specially devised 

 experiments, but by association in the ordinary 

 environment." (i). Thus it is evident that the 



