936 



THE KIDNEYS. 



Fig. 658. 



and ureter, may be traced into the sinus of the kidney, where they lie 

 amongst the infundibula, together with which they are usually imbedded 



in a quantity of fat. Penetrating the sub- 

 stance of the organ between the papilla?, the 

 arterial branches enter the cortical substance 

 found in the intervals between the medullary 

 cones, and go on, accompanied by a sheathing 

 of areolar tissue derived from the proper 

 coat, and dividing and subdividing, to reach 

 the bases of the pyramids, where they form 

 arches between the cortical and medullary 

 parts, which however are not complete, and 

 in this respect differ from the freely anasto- 

 mosing venous arches which accompany 

 them. From the arches smaller interlobular 



Fig. 658. INJECTED GLOMERULUS FROM THE INNER 

 PART OP THE CORTICAL SUBSTANCE OF THE HORSE'S 

 KIDNEY (from Kolliker after Bowman). \. 



a, interlobular artery ; a/, afferent artery ; ra m, 

 convoluted vessels of the glomerulus ; ef, efferent or 

 straight arteriole ; b, its subdivision in the medul- 

 lary substance. 



arteries are given off, which pass outwards 

 between the double layers of Malpighian cap- 

 sules which intervene between the pyramids 

 of Ferrein ; and from these interlobular arteries 

 are derived the afferent arteries of the glo- 

 meruli. The renal arteries give branches 

 likewise to the capsule of the kidney which 

 anastomose with branches of the lumbar ar- 

 teries, and that so freely that Ludwig was able 



partially to inject the kidneys of a dog from the aorta after the renal arte- 

 ries had been tied. (See also Turner as cited at p. 417.) Within the 

 glomerulus the afferent artery breaks up into convoluted branches of very 

 small size, which are gathered together again to form the efferent vessel. 

 The efferent vessel is so far comparable with the vena porta3 of the liver 

 that it breaks up again into capillaries, which form a close honeycomb net- 

 work surrounding the convoluted tubules, and a less copious network with 

 elongated meshes round the straight tubes of the cortical substance. Within 

 the medullary substance are found numbers of straight vessels, vasa recta, 

 which lie between the uriuiferous tubes, and at the bases of the Malpighian 

 pyramids are arranged in bundles extending inwards from between tha 

 pyramids of Ferrein. These vessels partly break up into capillaries, from 

 which returning veins arise, and partly, as has been already noticed, 

 form loops similar to those of the looped tubules of Henle. The mode 

 in which the va?a recta take origin has been made the subject of con- 

 Fiderable discussion. According to Bowman, Kolliker, and Ludwig and 

 Zawarykin, the vasa efferentia from the innermost glomeruli are larger 

 than the others, and break into brushes of these vasa recta. Arnold, 

 Virchow, Beale, and others maintain the direct origin of vasa recta from 

 the renal arteries without intervention of the glomeruli. Huschke, Henle, 



