412 



THE KIDNEYS. 



of a dog from the aorta after the renal arteries had been tied. Within 

 the glomerulus the afferent artery fig. 297, {af) breaks up into con- 

 voluted capillary branches, which are gathered together again to form 

 the efferent vessel {ef). The eflFerent vessel is so far comparable with 

 the vena portaa of the liver that it breaks up again into capillaries, 

 which form a close honeycomb network surounding the convoluted 

 tubules (fig. 295, e'), and a less copious network with elongated meshes 

 round the straight tubes of the cortical substance. Within the medullary 



Fig. 298. Fig. 298. —Longitu- 



dinal Section of a 

 Part of the medul- 

 lary Substance and 

 the adjacent Cor- 

 tical Substance op 

 the Kidney, show- 

 ing the blood-ves- 

 sels injected (from, 

 Southey). 



The figure is design- 

 ed principally to show 

 the origin of the vasa 

 recta. A A, ascending 

 arteries divided longi- 

 tudinally ; A a, trans- 

 verse section of anasto- 

 motic arch ; C V, cor- 

 tical veins ; m, glome- 

 ruli ; R R, artery rectae; 

 M Y, R medullary veins. 



substance are 

 Ibund numbers of 

 straight vessels, 

 vasa recta, which 

 lie between the ur- 

 iniferous tubes, 

 and, at the bases 

 of the Malpighian 

 pyramids, are ar- 

 ranged in bundles extending inwards from between the pyramids of 

 Ferrein. These vessels partly break up into capillaries, from which 

 returning veins arise, and partly form loops similar to those of the 

 looped tubules of Henle. The vasa recta take origin partly from the 

 vasa eflferentia from the innermost glomeruli (fig. 296, ar' ; fig. 297, h), 

 partly from the renal arteries without intervention of the glomeruli 

 (fig. 296, ar). 



Small veins, arising by numerous venous radicles from the capillary 

 network of the kidney, are seen near the surface of the gland, and 

 collect the blood fi'om the capillary plexus around the convoluted 

 tubules which mainly compose this part. These vessels, some of which 

 have a stellate arrangement {stellulm, Verheyen, fig. 296, vs), are joined 

 by numerous branches from the fibrous coat of the kidney, and, passing 

 through the cortical substance, end in larger veins, which again unite 

 into arches around the bases of the pyramids of Malpighi. The arches 

 receive the interlobular veins (fig. 296, vi) which accompany the inter- 



