710 O. D. ANDERSON 



normal level of performance (80 per cent). The average mag- 

 nitude showed a very definite increase (9 to 17) and this 

 value also declined after withdrawal of the extract (to 12). 



A slight rise in the magnitude of the C-R was observed 

 on the fifth day after administration of the extract was 

 begun. The maximal increase was not observed till the twelfth 

 day, the last day of the treatment. Two days after the sub- 

 stance was withdrawn, the reading was still slightly above 

 normal, and subsequent values were within normal range. 

 No behavioral change outside the laboratory was detected. 



TABLE 19 

 Dog C-l $ 



TRAINING ; DUR ^ G r t T N A T R E Y RI0R AFTER EXTRACT 

 PERIOD BXTRACT WITHDRAWN 



Correct responses to positive Met. 120 86% 90% 80% 



Average magnitude of C-R to positive 



Met. 120 9 17 12 



It is interesting to note that an effect upon the C-R was 

 detectable following the administration of anterior pituitary 

 extract. To attempt an explanation of such effect, based on 

 observations on one animal only, would presume too much. 

 The result, however, furnishes a basis for further work. 



The Effect of Hypophysectomy 



Dog 492 6 , bassethound X shepherd — bx bassethound. Both 

 the salivary and the motor C-R were formed and studied 

 in this dog prior to the operation. The former was established 

 to Met. 120, while the latter was established to a tone of 256 

 cycles. It was found best, however, to study one reflex at a 

 time. Thus the salivary reflex was observed for a few weeks, 

 then the motor reflex for a similar period, and so on. Negative 

 differential stimuli were not used. The duration of the train- 

 ing period was 3 months. 



This dog had been reared as a pet and was therefore 

 accustomed to handling. He was a gentle animal, showing- 

 no evidence of shyness, and his calm, even phlegmatic dis- 



