168 CORTEX 



which the concentration of the injected dye is determined. If 

 the period of time is too long, the dye will be lost from the 

 circulation; if too short, it will not mix properly with the blood. 

 In adrenal insufficiency, the circulation is slowed and hence 

 one is not justified in using the same period of time as one does 

 in normal animals. We must therefore disregard the extant 

 data on the blood volume in adrenal insufficiency and rely on 

 the other findings which indicate a decrease in this function. 



ALTERED SENSITIVITY 



Animals in adrenal insufficiency are hypersensitive to many 

 extraneous influences. This abnormal sensitivity to toxins 

 and infections will be considered in detail in Chapter XVII. 

 Insufficiency also renders animals hypersensitive to such in- 

 fluences as heat or cold, muscular exercise, emotional dis- 

 turbances, and the like. 



Adrenalectomized animals are unable to maintain their body 

 temperature when cooled. Thus de Marval 442 found that on 

 subjecting rats to an external temperature of 10°C. their rectal 

 temperature dropped 5.9° as compared to 2.5° for normal ani- 

 mals. The metabolic rise, which normally follows subjection 

 to cold, does not occur in adrenal insufficiency. 219 



One can markedly reduce the survival period of adrenalec- 

 tomized animals by subjecting them to extremes of tempera- 

 tures. Animals which normally survive for a week can be 

 thrown into an, acute and fatal insufficiency by subjecting 

 them for a few hours to temperatures which the normal ani- 

 mal can endure with impunity. 279 



Adrenalectomized animals are unable to withstand severe 

 muscular exercise and are easily precipitated into insufficiency 

 by exertion. A brief period of struggling may bring on the 

 final stages of insufficiency. 



The adrenal cortical hormone is essential for the normal 

 activities of the organism and hence an excessive manifesta- 



