CHEMICAL CONSTITUENTS 291 



tabolism, or that the lipids of the adrenal perform an indis- 

 pensable function in the organism are no longer tenable. The 

 fact that adrenalectomized animals maintained on lipid-free 

 extracts manifest no abnormalities attributable to the absence 

 of the adrenals proves that although the adrenal lipids are 

 probably essential parts of the cells, they are neither the 

 product of these cells nor is the adrenal tissue per se necessary 

 for the normal lipid metabolism of the organism. 



CHOLINE AND ACETYLCHOLINE 



Hunt 324 first demonstrated the presence of choline in ex- 

 tracts of the adrenals and demonstrated that such extracts 

 contained a substance which readily yields choline on chemical 

 manipulation. Since choline is a product of the hydrolysis 

 of the phosphatides, it is found wherever the ubiquitous 

 lecithin occurs and it is often very difficult to decide whether 

 the choline obtained from an organ was originally present as 

 such or was derived from lecithin. 



Feldberg and Schild 193 found acetylcholine to be more abun- 

 dant in the medulla than in the cortex, the proportion varying 

 from 2.5:1 to 4.5:1. The reverse relation held for choline. 

 These authors (Chapter VI) also demonstrated the secretion 

 of choline from the adrenals during stimulation of the splanch- 

 nic nerves. 



The presence of choline in the adrenals has led authors to 

 assume that this substance is an important product of the 

 gland and some have even hypothecated that it is the cortical 

 hormone. There is nothing to support these views nor is there, 

 except for the experiments just cited, any evidence to indicate 

 that choline or its esters play any significant role in the ad- 

 renals. These substances may, however, contaminate crude 

 adrenal extracts. Some of the pharmacodynamic effects of 

 such extracts described in the literature are undoubtedly to be 

 attributed to the presence of choline rather than to the cortical 

 hormone.' 68 The biological assay of the epinephrine content 



