GENETIC TYPE AXD THE EXDOCRIXES 



685 



gained its normal value. One year after the operation the thy- 

 roid region was again exposed surgically. The left thyroid lobe 

 had hypertrophied enormously (approximately 20 times). 

 The lobe was then completely removed, leaving behind only 

 the parathyroid body. When the C-R was again tested it was 

 found absent in almost every trial and did not revive during 

 5 months of testing. The autopsy showed complete absence 

 of thyroid tissue. The parathyroid body was present. 



At the stage of maximal thyroid deficiency, the general 

 behavior picture was typical for the condition. Although 

 general activity was impaired for a time, the dog suffered 

 no loss of appetite. 



TABLE 13 

 Dog 864 <$ 



Correct responses to positive Met. 120 

 Correct responses to negative Met. 42 

 Correct responses to negative Met. 28 

 Average magnitude of C-R to positive Met. 120 



AFTER 

 COMPLETE 

 THYROID- 

 ECTOMY 



30% 



80% 



The results presented in table 13 are almost the exact 

 duplicate of those in the previous experiment. The efficiency 

 of the positive C-R very noticeably decreased (88 per cent 

 to 54 per cent) after the first operation and decreased further 

 after the second (54 per cent to 30 per cent). From a very 

 low percentage, the correct responses to the negative Met. 

 42 increased enormously (5 per cent to 77 per cent) and this 

 increase was maintained after the second operation (80 per 

 cent). This was largely due to a lack of response to any 

 stimulus rather than to an "appreciation" of the negative 

 metronome. The negative C-R to Met. 28 was also increased 

 (30 per cent to 85 per cent). 



The magnitude of the positive C-R dropped after the first 

 operation (9 to 3) and showed a further decrease after the 

 second (to 1 ). 



