766 THE SUPRARENAL CAPSULES. [BOOK n. 



of the coarser connective tissue septa. Hence the main median 

 part of the cortex, which from the prominent columnar arrange- 

 ment appears striated radially, is often called the zona fasciculata, 

 the thin outer part the zona glomerulosa, and the thin inner part 

 the zona reticularis ; but as far as the essential characters of the 

 cells are concerned all the three zones are alike. 



The medulla also consists of cells or groups of cells lying in 

 the meshes of a connective tissue frame-work, but the cells are of 

 a different nature from those of the cortex. They are irregular 

 and often branched, and their cell-substance, though it sometimes 

 contains pigment, is generally clear and transparent. The medulla 

 moreover is further distinguished from the cortex by the abundant 

 supply of blood vessels and of nerves. 



The cells of the medulla and of the inner zone (zona 

 reticularis) of the cortex are very apt to undergo change after 

 death, and to become diffluent. 



The arteries which come from the aorta and from the renal and 

 phrenic arteries pass into the organ on the surface, and traversing 

 the cortex, supplying as they go both capsule and cortex with a 

 moderate number of vessels, end in the medulla, the connective 

 tissue bars of which bear numerous large venous sinuses, into 

 which the capillaries pour their blood, and from which the blood 

 is gathered up into the suprarenal vein. 



A large number of nerves, consisting chiefly of medullated 

 fibres from the solar plexus, the renal plexus, the phrenic nerve 

 and the vagus, pass into the suprarenal body at the hilus and on 

 the under surface, and forming numerous plexuses coarse and fine, 

 some carrying small groups of nerve cells, end chiefly in the 

 medulla, though some pass on to the cortex. The ultimate 

 endings are not yet known. 



The lymphatics are fairly numerous and form plexuses in the 

 capsule and in the connective tissue of the frame-work; it is 

 stated that the lymphatic vessels surrounding the groups of cells 

 in the cortex communicate with spaces between the cells. 



498. Besides the ordinary proteid and other chemical 

 constituents, the suprarenal body contains some substance or 

 substances, possessing striking colour reactions, giving a dark blue 

 or dark green colour with ferric chloride, and a carmine red tint 

 with various oxidizing agents. This substance (whose nature is 

 not exactly known, and which is confined to or most abundant in 

 the medulla) is not soluble in the ordinary solvents of pigments, 

 such as alcohol, ether, chloroform &c., but is readily soluble in 

 dilute acids. 



Among the extractives, hippuric, or benzoic acid, and tauro- 

 cholic acid or taurin have been found, but it is not certain that 

 these are normal constituents. 



499. Some of the histological features of the suprarenal 

 bodies, namely the groups of cells and their abundant blood supply, 



