GENETIC TYPE AND THE ENDOCRINES 



689 



but this declined after the extract was withdrawn (to 13 per 

 cent). It increased again during the second thyroid period 

 (to 58 per cent) and again declined afterward (to 39 per cent). 

 During the third thyroid period it was again enhanced (to 

 62 per cent), and when the substance was withheld it dropped 

 enormously (to per cent). 



The magnitude of the C-R followed the same course almost 

 exactly. During the first thyroid period the average response 

 was of medium strength (3). In the next period the value 

 dropped markedly (to less than 1) ; in the next, during which 

 double the amount of thyroid substance was given daily (2 

 gms. instead of 1 gm.), the value became more than double 

 that of the first period (7). After this the average declined 



TABLE 14 

 Bog 1030 <$ 



DURING 



FIRST 

 THYROID 

 EXTRACT 



PERIOD 



Correct responses to 



positive Met. 120 63% 



Average magnitude of C-R 



to positive Met. 120 3 



13< 



DURING 

 SECOND 

 THYROID 

 EXTRACT 

 PERIOD 



58% 



7 



39% 

 5 



DURING 



THIRD 



THYROID 



EXTRACT 



PERIOD 



0% 

 



(to 5). It was increased again during thyroid injection (to 

 7) but this was not proportional to the further increase in 

 the amount of the extract given (3 gms. daily). In the final 

 phase, when no extract was given, the magnitude decreased 

 greatly (to 0). 



The animal 's general condition appeared to be considerably 

 worse with each succeeding period of thyroid deprivation. 

 In the second period, trophic disturbances of the skin, 

 myxoedema associated with mange, developed in addition 

 to the neuro-muscular symptoms. The skin was greatly 

 wrinkled, puffy, dry, scaly and nearly hairless. In the last 

 period the skeletal muscle reflexes were exceedingly slow. 

 It was very interesting to note the retardation, for example, 

 in the reaction of shaking the bodv. The normal dog, when 



