GENETIC TYPE AND THE ENDOCRIXES 699 



to -1). No change in general behavior was noted either in 

 or outside the laboratory. 



These results indicate that the level of excitability is slightly 

 raised during the administration of small doses of para- 

 thyroid extract. Positive efficiency shows a percentage in- 

 crease, while the negative shows a slight decrease in one 

 case and a considerable increase in the other. The magnitude 

 of the reflex is of significance here. 



In brief, it may be stated that in both animals the efficiency 

 and magnitude of the positive C-R were slightly increased. 

 In one, the efficiency of the negative C-R diminished some- 

 what, its magnitude remaining about the same. In the other 

 the efficiency of this response increased considerably, while 

 its magnitude definitely decreased. The former animal became 

 more restless in the experiment, while the latter showed no 

 change in general behavior. 



THE EFFECT OF COMPLETE THYRO-PARATHYROIDECTOMY 



Dog 869 9 , bassethound X shepherd F 2 . An account of the 

 training period and the period following partial thyroidectomy 

 in this dog has been discussed above in connection with the 

 thyroid effects. It will be recalled that the positive motor C-R 

 decreased sharply after the removal of the greater part of 

 the thyroid and that the response gradually improved ac- 

 companying the natural regeneration of the small portion 

 of thyroid tissue left behind along with the parathyroids. 

 At this stage of the experiment thyro-parathyroidectomy was 

 performed. Subsequent autopsy showed the complete absence 

 of the thyroids and parathyroids. 



