274 CORTEX 



One can assume that in Rich's experiments sufficient amounts 

 of the hormone remained in the organism after adrenalectomy 

 to prevent the onset of shock for some time. 



Austmann, Halliday, and Vincent 25 kept dogs under ether 

 for as long as 40 hours after removing both adrenals without 

 any marked fall in blood pressure. Bazett, 47 on the other hand, 

 found that although excision of the adrenal glands in cats 

 causes no immediate fall in blood pressure, the extirpation 

 hastens the onset of the fall which ultimately occurs in animals 

 maintained for long periods under anesthesia (urethane) or 

 after decerebration. This was particularly striking in the 

 decerebrate preparations which normally maintain their blood 

 pressure for several days if the body temperature be kept nor- 

 mal. After excision of the adrenals, however, the blood pres- 

 sure falls after about an hour and death occurs within ten hours 

 after the operation. 



Injection of histamine causes a drop in blood pressure similar 

 to that observed in shock. The adrenalectomized cat, as 

 Dale 147 showed, is extremely sensitive to histamine. Although 

 a normal, unanesthetized cat can tolerate an infusion of hista- 

 mine in doses up to at least 10 mgms. per kilo., without severe 

 effects, the same animal on the day following bilateral adrenal- 

 ectomy is killed by doses as small as 0.16 mgms. per kilo. 

 Anesthesia, likewise reduces the resistance of the cat to hista- 

 mine. After an hour's administration of ether, 1 or 2 mgms. 

 of histamine per kilo of body weight will induce the fatal shock 

 characteristic of histamine poisoning. 



Dale pointed out that the "circulatory condition developing 

 in the 24 hours following removal of the adrenals has features 

 in common with that produced by histamine, including a pro- 

 nounced increase in the proportion of corpuscles in the blood." 

 As Dale recognized, it was impossible by his experiments to 

 determine whether the absence of the medulla or the cortex was 

 responsible for the decreased resistance towards histamine of 

 the adrenalectomized animal. Histamine stimulates epineph- 



