734 O. D. ANDERSON 



of the limb. On the next day no extract was given and the 

 animal sank rapidly. He lay upon his side and did not raise 

 the head or otherwise react either when called or when the 

 above stimuli were tried again. The conditioned reflex tests 

 were, of course, abandoned, due to the depth of the stupor 

 and prostration. The dog died on the day following and the 

 autopsy showed a complete absence of suprarenal tissue. 

 Just as the injection of parathyroid substance in an animal 

 which had been thyro-parathyroidectomized raised the values 

 of the C-R, so in the present experiment the injection of 

 suprarenal cortical extract partially restored the reflex in 

 an animal with the adrenals removed. The incomplete restora- 

 tion points to a lack of medullary substance, adrenalin. We 

 interpret the decline in the responsiveness of the animal to 

 stimulation following adrenalectomy to a decline in the level 

 of general excitability for these reasons : An active, excitable 

 dog with a well established motor conditioned reflex when 

 bilaterally adrenalectomized shows deterioration of the reflex 

 as well as general activity, and is changed from super-active 

 to sluggish and apathetic. Injection of suprarenal cortical 

 extract restores the efficiency of the reflex to its former level 

 and partially restores its magnitude and also gives improve- 

 ment in the general behavior. 



PLATE 112 



EXPLANATION OF FIGURES 



1 Vigorous motor (defensive) reactions of dog 1398 prior to adrenalectomy. 

 The defensive head, body, respiratory and leg reactions were initiated by the 

 Met. 120 followed by the shock. Note that the responses were so violent that 

 they continued even after the stimulus was Avithdrawn. 



2 The effect of bilateral adrenalectomy on the motor reactions in dog 1398. 

 Notice that the first application of the metronome and shock evoked no response 

 whatever, while the second evoked a very weak reaction of the head, respiration 

 and limb. 



3 The return of the vigorous defensive behavior in dog 1398 after the ad- 

 ministration of an extract of the suprarenal cortex (eschatin). The head, body, 

 respiratory and leg reactions are almost as vigorous as before the operation. 



