GENETIC TYPE AND THE ENDOCRINES 575 



in specifying the dogs with definite temperaments. Many of 

 the dogs used by Pavlov were undoubtedly mongrels. In 

 many cases these animals have behavioral characteristics of 

 both polar groups, and thus there is great difficulty in under- 

 standing them. Unless one knows the genetic background of 

 the animal for many generations, its behavior cannot be 

 understood. Behavior is similar to physical form in this 

 respect; a physical characteristic can be observed, but its 

 significance cannot be understood unless the genetic back- 

 ground of the animal is known. 



It will be of interest to observe the behavior of these 

 animals under other conditions. The salivary response gives 

 an indication of the reactions centering around the more or 

 less "unconscious" or "volitionally uncontrolled" actions 

 of a gland. For a further understanding of our problem, a 

 behavior involving one of the more voluntary muscular types 

 of performance will be of interest. 



ANALYSIS OF BEHAVIOR IN A CONDITIONED 

 AVOIDING SITUATION 



In order to obtain a true picture of motor performances, 

 the reaction to be studied should have the characteristics of 

 voluntary behavior yet enable the experimenter to control it 

 as specifically as, or even more specifically, then the food 

 taking behavior. Voluntary control in this case means that 

 the performance may be dominated to a greater extent by 

 higher nervous centers than the food taking processes. The 

 withdrawal of the foreleg from a painful irritation has been 

 used to advantage in many experiments, and this reflex 

 system is employed in the present study. Animals from each 

 of the four groups classified in the food taking experiments, 

 and others, chosen for various reasons, were trained for this 

 experiment. 



The procedure in this experiment was to train the dog to 

 raise the foreleg to a specific signal (bell, buzzer, or clicker) 

 and thereby avoid an electric shock. The shock was applied 

 by means of electrodes attached to the dog's right wrist; 



