34 2 THE GENITO-URINARY ORGANS. 



medulla to form small anastomosing veins, from which the larger 

 veins are derived. The latter do not anastomose, and are therefore 

 terminal veins. The arteries of the medulla pass through the 

 cortex without giving off any branches until the medulla is reached, 

 where they break up into a capillary network surrounding the cell 

 masses situated here. The blood from this plexus may be col- 

 lected into veins of the medulla which empty into the terminal 

 vein or some of its larger branches, or may flow directly into 

 branches of the venous tree. The endothelial walls of the capil- 

 laries rest directly on the specific gland cells, with the intervention 

 here and there of a few reticular fibrils. According to Pfaundler, 

 the walls of the blood-vessels of the entire suprarenal body consist 

 solely of the tunica intima. 



The nerves of the suprarenal glands have been studied recently 

 by Fusari and Dogiel (94) ; the description given by the latter will 

 here be followed. Numerous nerve-fibers, both nonmedullated and 

 medullated, arranged in the form of a plexus containing sym- 

 pathetic ganglia, are found in the capsule. From this plexus 

 numerous small bundles and varicose fibers enter the cortex, where 

 they form plexuses surrounding the columns of cells or groups of 

 cells found in the three zones of the cortex and about the vessels 

 and capillaries of the cortex. The nerve-fibers of these plexuses are 

 on the outside of the columns and cell groups and do not give 

 off branches which pass between the cells. The nerve supply of 

 the medullary substance is very rich, and is derived mainly from 

 large nerve bundles which pass from the plexus in the capsule to 

 the medulla, where they divide and form dense plexuses which 

 surround the groups of gland-cells and veins ; from these plexuses 

 fine varicose fibers pass between the gland-cells, forming intercel- 

 lular plexuses. In the medulla there are found in many animals 

 large numbers of sympathetic cells, some isolated, others grouped 

 to form small ganglia. Pericellular networks surround the cell- 

 .bodies of certain of these sympathetic cells. (For further informa- 

 tion concerning the suprarenal glands consult Gottschau, Weldon, 

 Hans Rabl, C. K. Hoffmann (92), Pfaundler, Flint, and Dogiel.) 



TECHNIC 



Kidney. The arrangement of the cortical and medullary portions 

 of the kidney is best seen in sections of the kidney of small mammalia, 

 cut in the proper direction, and, if possible, embracing the whole organ. 

 If, on the other hand, the finer epithelial structures are to be examined, 

 small pieces are first fixed in osmic acid mixtures or -in corrosive 

 sublimate. 



Impregnation with silver nitrate (method of Golgi or Cox) 

 reveals some points as to the relation of the cells of the uriniferous tubules 

 to each other. 



In order to isolate the tubules, thin strips of kidney tissue are 

 treated for from fifteen to twenty hours with pure hydrochloric acid 



