ADDISOX'S DISEASE 285 



A comprehension of the dual nature of the suprarenal gland and of 

 the occurrence of suprarenal tissue in various regions of the body, apart 

 from the suprarenal gland proper, is indispensable to a clear understanding 

 of the modern conception of the pathogenesis of the disease. The anato- 

 mists have shown that each human suprarenal is formed of two compo- 

 nents, the cortex and the medulla, which differ from each other in morpho- 

 logical structure. In the lower vertebrates these components represent two 

 separate and independent series of organs. The medulla of the gland is of 

 neuroectodermal origin, derived from the anlage of the sympathetic system, 

 and forms a part of the so-called chromaphil system, while the cortex 

 is of mesodermic origin, and belongs to the interrenal system of organs. 

 In mammals a mass of chromaphil cells (so called by virtue of their re- 

 action to chromium salts) has become enclosed within the cortical tissue, 

 forming the suprarenal gland. According to Kohn(&) the medullary sub- 

 stance is not properly a part of the suprarenal body, but simply a mass 

 of chromaphil cells which have become insinuated into the suprarenal 

 proper, or cortex. The suprarenal medulla represents only a portion of 

 the chromaphil system of the body, and there is some reason to believe 

 that there is more chromaphil tissue outside of the suprarenal glands 

 than within them, since it is widely distributed in the body, occurring 

 in the paraganglia of Kchn, the carotid gland, the plexus ganglia, and 

 in the so-called accessory body of Zuckerkandl, and in minute masses along 

 the sympathetic trunks. Stewart (1912), however, has cited evidence that 

 the extra-suprarenal chromaphil tissue comprises but a small fraction 

 of the total. The cortical tissue (interrenal system) is represented out- 

 side of the suprarenal proper by the so-called accessory "interrenal" bodies, 

 which are also widely distributed, but less regular and constant in their 

 occurrence than the chromaphil bodies. According to Schmorl accessory 

 suprarenals are found in about 92 per cent of human cadavers. They are 

 most commonly found at the hilus of the kidney, or within the kidney 

 substance, along the suprarenal veins, and associated with the internal 

 genitalia. True accessory suprarenals, formed of both cortical and medul- 

 lary substance, are extremely rare. It is, moreover, believed that these two 

 systems, the chromaphil (medulla) and interrenal (cortex) have entirely 

 separate functions. Some observers regard the fusion of the two com- 

 ponents in the higher vertebrates as having a physiological significance con- 

 cerning the function of the gland as a whole, but no proof of this has been 

 obtained. It has also been assumed, with respect to function, that what can 

 be proven true of one part of the chromaphil or interrenal systems may be 

 regarded as obtaining for the other portions of these systems. A pressor 

 substance, similar to that found in the medulla, has been demonstrated in 

 the extra-suprarenal chromaphil tissue by Biedl(/) and others. 



It is, therefore, apparent that any consideration of the altered function 

 of the suprarenal gland, as a basis for the interpretation of the phenomena 



