276 C. N. H. LONG 



this system a hormone, vitamin, and protein enzyme are all part of a 

 cellular mechanism for carbohydrate metabolism. 



Finally it may be pointed out that there is an excellent degree of cor- 

 relation between the decline in adrenal cholesterol and ascorbic acid and 

 such tangible and well-authenticated manifestations of adrenal cortical 

 activity as the increase in liver glycogen in fasting animals and the fall 

 in the number of circulating lymphocytes. 



It is therefore possible not only to use these changes in the chemical 

 composition of the adrenal as indicators of increased secretory activity 

 but also under the right conditions to employ them as a method for the 

 assay of the adrenotrophic hormone itself. For this last purpose it is 

 desirable to use hypophysectomized animals as the test objects, since 

 their adrenal cholesterol and ascorbic acid will be affected only by the 

 trophic hormone and not by any nonspecific agent in the material in- 

 jected. By the use of such a method Dr. and Mrs. Sayers, now at the 

 University of Utah, have found that the blood level of adrenotrophic 

 hormone in normal rats is from 10-15 micrograms per 100 mis. and 

 that a rat pituitary gland contains about 20 micrograms of the hormone. 

 It should now be possible to apply this method to the determination of 

 the level of adrenotrophic hormone in the body fluids, a procedure that 

 should be of particular value in the diagnosis of certain endocrine dis- 

 orders in man. 



We have already made a considerable number of observations on the 

 effect of various procedures on the secretory activity of the adrenal 

 cortex. In most of these experiments we have been satisfied to deter- 

 mine only ascorbic acid, since it reflects any change more rapidly than 

 cholesterol. We have found that exposure to cold (4°C for i hour), 

 trauma to muscles and particularly to the long bones, painful stimuli, 

 cutting or bruising the skin, burns, the intraperitoneal injection of cold 

 isotonic saline or other fluids, and the inhalation of volatile anesthetics, 

 all cause an immediate and prompt increased rate of secretion of the 

 cortical hormones (10). As might be expected, the degree of activation 

 of the gland is determined by the intensity and duration of the stimulus 

 applied. 



We come now to an interesting and important point concerning the 

 manner in which these diverse types of stimuli bring about an increased 

 degree of cortical secretion. Three recent investigations bear on this 

 point. 



(a) We have found that epinephrine, which, is certainly released after 

 the most varied types of stress, causes within an hour after subcutane- 



