GENETIC TYPE AND THE ENDOCRINES 681 



when approached by a stranger she often ran away to hide. 

 She represented the all-around, well balanced behavior type. 



The motor C-R appeared initially at the second combination 

 of the metronome and shock and thereafter it occurred in 

 116 cases out of 120. 



In the previous experiment, the weakened reflex was re- 

 vived by thyroid injections. To test whether a small bit of 

 thyroid tissue left behind at operation would, after a time 

 and through regeneration, restore the reflex, the present dog- 

 was partially thyroidectomized. The upper portion of each 

 thyroid lobe was removed, leaving behind portions about the 

 size of a pea. The external parathyroid bodies were not 

 removed. 



The results were striking. The strong motor C-R declined 

 to after the operation. Within 3 months, however, the 

 response was gradually built up to almost normal without 

 the aid of thyroid injections. At this point, the site of the 

 operation was reopened and the bit of thyroid tissue on each 

 side was found to be greatly hypertrophied (about doubled). 

 Complete thyroidectomy was then performed. The results 

 of this latter phase of the experiment will be reported under 

 another heading. 



TABLE 12 

 Bog 869 ? 



TRAINING AFTER 1' \I:TI \1. 



PERIOD THYROIDECTOMY 



Correct responses to positive Met. 12H 



< forrect responses to negative Met. 42 17% 45<% 



Correct responses to negative Met. 28 



100% 



Average magnitude of C-R to positive Met. 120 46 23 



As shown by table 12, the efficiency of the positive C-R 

 declined (97 per cent to 82 per cent) while that of the negative 

 C-R to Met. 42 rose (17 per cent to 45 per cent). Negative 

 responses to Met. 28 were unchanged. The magnitude of the 

 positive reflex decreased (46 to 23). 



The results are shown graphically in text-figure 121 and 

 122. Text-figure 121 (fig. 1) is a record of the positive con- 



