GENETIC TYPE AND THE ENDOCEIXES 677 



case, as the motor C-R became more vigorous the animal 

 became extremely nervous. 



In the case in which the efficiency of the salivary C-R was 

 decreased, the animal, a "neurotic" dog, exhibited general 

 reactions of a most violent sort during the administration 

 of the extract. 



THE EFFECT OF THYEOIDECTOMY 



Dog 866 $ , bassethoimd X shepherd F 2 . The conditioned 

 stimuli were Met. 120 (positive) and Met. 42 and Met. 28 

 (negative). The C-R was standardized for 13 months before 

 the operation. 



This dog represented the well-behaved type. He was gentle, 

 friendly, and cooperative, being obedient to gesture; in addi- 

 tion, he was lively and active but somewhat aggressive with 

 other dogs. He showed no evidence of shyness under any 

 circumstances. 



A relatively constant salivary C-R was formed in seventeen 

 trials. The dog was then completely thyroidectomized without 

 removing the external parathyroids. Behavior was studied 

 for 6 months after the operation. 10 



The C-R vanished almost completely after the operation. 

 It was revived by the continued administration of thyroid 

 extract. When the extract was withdrawn the C-R again 

 disappeared. 



The typical general behavior of the hypothyroid individual 

 was presented. As the neuro-muscular lethargy set in, a 

 considerable decrease in the animal's general activity was 

 noticed. He was less alert than before in his reactions to 

 both the experimenter and to the dogs. He slept during much 

 of each day, and often could not be aroused by calling him 

 by name. He paid little attention to the other dogs about 

 him, never barking, playing or fighting with them as had 

 formerly been his wont. He was, however, almost normally 



10 The C-R tests were never resumed immediately after the operation ; to allow 

 recovery from post-operative trauma at least 5 days elapsed before again starting 

 them. 



