i INTERNAL PROTECTIVE SECRETIONS 47 



sular sheath at various points, after subdividing into small 

 branches. The veins in the medullary substance form a plexus, 

 and usually converge into one large vein for each organ, which 

 leaves by the hiluin. That on the right opens directly into the 

 inferior cava ; that on f;he left, after a longer course, into the left 

 renal vein. 



According to Pfaundler, the internal vessels of the suprarenals 

 have no proper tunica externa and media, only a thin wall consist- 

 ing solely of intinia. 



The lymphatics course through the trabeculae of the cortical 

 substance, and are connected with the lacunae or fissures lying 

 between the trabeculae and the columns of cells, and between the 

 cells themselves (Klein). In the medullary substance the lymph- 

 atics, which are provided with valves, form a plexus that interlaces 

 with the venous plexus, and surrounds the central vein. 



Both suprarenal bodies and paraganglia contain an enormous 

 number of nerves deriving from the solar and the renal plexuses 

 (Fig. 15). They are mainly medullated fibres of different sizes, 

 interspersed before entering the capsule with a number of small 

 ganglia. They ramify between the cells of the cortex, and are 

 most abundant in the zona glomerulosa. In the medulla there 

 are many ganglion cells united in groups, and nerve fibres, 

 which are distributed to the vessels and also perhaps to the 

 gland-cells. 



In rare cases one or both suprarenal bodies are absent. More 

 frequently there are accessory adrenals, which vary in size from a 

 pin's head to that of a pea. The smallest have no medullary 

 substance (Rolleston). These accessory capsules are usually found 

 in the neighbourhood of the capsule itself ; but they are sometimes 

 partially embedded in the kidney or liver, the broad ligament of 

 the uterus, and along the spermatic vessels. 



In 1789 Cassan observed that the suprarenal capsules are 

 larger in the negro than in Europeans, which led him. to suspect 

 that these organs are in some relation with the formation of 

 cutaneous pigment. Meckel subsequently confirmed Cassan's 

 observations, but held the greater development of the capsules 

 in negroes to be in relation with that of the genital organs. 

 These anatomical observations of Cassan and Meckel are in line 

 with the work of Addison, published in 1855, which promoted 

 experimental investigation of the suprarenal bodies, and may be 

 said to have initiated the physiological study of these glandular 



organs. 



XIII. Addison was the first to describe a form of disease 

 which is nearly always fatal, and is characterised by a state of 

 progressive anaemia, pronounced weakness of cardiac beat, 

 great irritability of stomach, and general atony of nervous and 

 muscular system, with abnormal brown or bronzed patches on 



