688 O. D. ANDERSON 



to the laboratory and lifted upon the platform (he was too 

 weak and stiff to climb upon it), simply did nothing at all 

 when the food was presented. He stood perfectly still with 

 his head held low. At times, when attempts were not being' 

 made to stimulate him, he lay upon the platform and slept. 

 When awake, he made no responses to stimuli such as the 

 Met. 120, the sound of a door buzzer or a flashing light. Light 

 touch stimulation applied to the flank by the Krasnogorski 

 skin stimulator (pneumatically actuated) evoked only the 

 shaking reflex of that region of the skin. Sniffing reactions 

 were evoked by a strong odor of oil of cloves. 



The results were the same during 41 days of behavior 

 testing in the laboratory. The dog ate food readily enough 

 at the regular daily feeding time in the kennel. 



At this point, the animal was fed thyroid extract, 1 gm. 

 daily for 57 days. The results during this time were also 

 definite and striking. Five days after the beginning of the 

 extract therapy the dog began to eat the food presented in 

 the laboratory. After 1 month, when the unconditioned food 

 reflex was considered to be normal, the trials were begun to 

 develop the C-R to Met. 120. The response was formed well 

 within the normal time in twenty-one trials, and it was main- 

 tained at a normal level during the first 25 days after the 

 extract was withdrawn. After this the reflex failed com- 

 pletely. 



The continued administration of thyroid substance to this 

 dog was tried on two other occasions with exactly the same 

 result. On one occasion, 2 gms. of the extract daily were 

 given subcutaneously for 41 days; and on another, 3 gms. 

 daily were given in the same way for 25 days. During each 

 period the C-R reappeared soon after the treatment was 

 initiated and was maintained normally throughout the period 

 and for a considerable time afterward. 



Table 14 shows the fluctuations of the conditioned reflex 

 during the alternate periods of thyroid sufficiency and de- 

 ficiency. The efficiency of the response was fairly high during 

 the first period of administration of the extract (63 per cent), 



