INTERNAL. SECRETION 501 



The gland is abundantly supplied with blood-vessels and nerves. The 

 rteries are branches of the aorta, the phrenic, and renal arteries. After 

 enetrating the gland they divide into smaller branches and capillaries which 

 Itimately come into close relation with the cells of both the cortex and 

 aedulla. The veins emerge from the gland at the hilum and empty on 

 tie right side into the vena cava and on the left side into the renal vein. 

 The nerves passing to the gland are derived for the most part from the 

 utonomic system. The pre-ganglionic fibers pass from the cord by way 

 f the splanchnics to the semilunar ganglion. The post-ganglionic pass 

 rom the semilunar ganglia through its branches direct to the gland. Ac- 

 ording to Bergmann nerves come from the phrenic and vagus also. 



Embryologic Development. Embryologic 

 avestigations have shown that the mature adre- 

 al gland consists of two distinct tissues derived 

 rom two different portions of the embryo. The 

 ortex is derived from that portion of the meso- 

 erm from which is evolved the precursor of the 

 idney, the Wolffian body; the medulla is de- 

 ived from the embryonic sympathetic ganglia 

 nd consists primarily of nerve-cells, which, 

 owever, in the course of development become 

 rofoundly modified. Comparative anatomic 

 tudies have shown the relation of these two 

 omponents of the adrenal body. In the elasmo- 

 >ranch fishes, the shark, ray, etc., the cortex is 

 epresented early by an internal body somewhat 

 od-shaped and elongated and situated toward 

 he posterior portion of the kidney. In the 

 )ony fishes this organ becomes paired. The 

 nedulla is represented by a series of paired 

 bodies extending along the vertebral column 

 ind in close relation to the sympathetic ganglia 

 and contain a number of chromaffin cells. 



These two elements unite to form the com- FlG> 225> _ SECTION OF HUMAN 

 xnmd adrenal. In the mammals the larger por- SUPRARENAL BODY, a, fibrous 

 ion of this chromaffin material fuses and be- capsule; 6, zona glomerulosa; c, 

 :omes enveloped on each side by the internal ^g^^5^SS 

 uody with the formation of the existing adrenal n ' e i ; gt ganglion-cells. (Piersol). 

 Dody. The unincorporated portions of the chro- 

 maffin bodies remain as masses of varying size, found in connection with 

 the sympathetic nerve system. The most important of these bodies is the 

 , ' abdominal chromaffin body" extending along the aorta from the level^of 

 the adrenals to the bifurcation. It is readily exposed in the dog by stain- 

 ing with a solution of bichromate of potassium. Accessory adrenal bodies 

 may consist of either cortical or chromaffin material alone or of both. 

 The Effects of Disease and Removal of the Adrenal Glands.- 

 ! is a profound disturbance of the nutrition first described by Addison and 

 subsequently termed by Trousseau, Addison's disease, which is characte 

 ized'by extreme muscular weakness and an incapacity for sustained muscle 

 activity a bronze-like discoloration of the skin and mucous membranes, dis 



