71() 0. I). ANDEKSON 



hands. Such food-taking- and defensive reactions have been 

 referred to by Pavlov as "natural" conditioned reflexes and 

 are to be distinguished from what is ordinarily understood 

 by the term "conditioned reflex." During the terminal phase 

 of the gland disturbance, however, such responses could be 

 aroused only rarely. 



The dog became gradually less active, and the movements 

 in walking, although coordinated, were slow. 



The autopsy showed no trace of pituitary tissue. 



Dog C-19 , bassethound X shepherd F 3 . This dog was se- 

 lected for a more exhaustive analysis of the effect of hypo- 

 physectomy on the C-R for the reason, mentioned before, 

 that the salivary response could be elicited with machine-like 

 precision in a relatively uniform and regular manner. The 

 control period thus offered an excellent standard for com- 

 parison (a high level of performance) with the post-operative 

 period. 



Description of the behavior of dog 0-1 during the training 

 period has already been given. The total length of the train- 

 ing period, including experiments on the administration of 

 parathormone, anterior pituitary extract and later adrenalin, 

 was 17 months. The C-R was completely standardized before 

 the operation was performed. 



A complete hypophysectomy was performed in this animal. 

 To obviate any possible effect of post-operative trauma, the 

 behavior tests were not resumed until after a lapse of 41 

 days, when it was found that the formerly efficient and vigor- 

 ous conditioned salivary reaction had disappeared completely. 



General anterior lobe pituitary extract (growth hormone — 

 Squibb), 20 units daily, was given subcutaneously for 19 

 days to determine whether the C-R could be revived, and if 

 so, to what extent. The response reappeared with almost 

 normal magnitude, but soon diminished and finally disap- 

 peared again even though administration of the extract was 

 continued. 



Since the thyroid frequently shows evidences of atrophy 

 after hypophysectomy, it was thought that the absence of 



