528 MANUAL OF HISTOLOGY. 



upon itself without undergoing division (c), leaving the capsule as an 

 efferent vessel (&). 



In man and the mammalia this efferent vessel breaks up into a net- 

 work of fine capillaries, with elongated meshes surrounding the straight 

 uriniferous canals of the medullary radii (iig. 522, k; 526, e). From the 

 periphery of this network a multitude of somewhat wider tubes is given 

 off (fig. 522, 1; 526, /), which, encircle with their rounded meshes the 



convoluted uriniferous tubes (?) of the 

 cortical substance proper (or cortical 

 pyramids (Stein, Key), and others). 



The most external layer of the cor- 

 tex is destitute of MaJpighian glome- 

 ruii. It receives its capillaries (fig. 

 522, /) principally from the efferent 



e a aim _***&? y-y vessels of the superficial glorneruli 



^ (e), and to a smaller extent, and un- 

 doubtedly in only some of the mam- 

 malia, from certain terminal twigs of 

 the arteries supplying the Malpighian 

 bodies, which pass forward directly to 

 this layer of the cortex. 

 Fig. 526.-From the kidney of the pig (half Immediately underneath the cap- 



diagramieatic). a, arterial twig ; 6, afferent sule microscopic V6I10US radicals may 



vessel of the glomerulus, c; d, vasefferens; , -, , , N . ,-, ,. f , -,, , 



e, subdivision of the latter, forming the long- be recognised (t) in the I0rm 01 Stellate 



meshed network of the medullary processes ; fjo-nrpq frfpJh/Jfp Vprhpiimih Othpr 



/, round meshes of capillaries around the ngures (SteilUlO, V 61 lieyeUU). U1116 



convoluted tubes f,- gr, radicle of a venous venous twigs take their origin deeper 



in the cortical tissue (fig. 522, 6), 



and both of these, joining usually to form larger trunks, empty themselves 

 at the boundary between cortex and medulla into the venous arches. 



Those long bundles of vessels which appear in the medullary substance 

 at its boundary, between the uriniferous tubes, running from thence down- 

 wards, and either communicating with each other in loops, or forming a 

 delicate network around the mouths of the uriniferous canals, at the apex 

 of the papillae, are known by the name of the vasa recta (fig. 509, e, /, 

 and 522, h, g, m). 



Between these, according to Ludwig and ZawaryJcin, there is inter- 

 posed another large meshed capillary network of finer tubes (n). This is 

 a continuation of the oval network which encircled the straight urini- 

 ferous tubes of the cortex. There still exists, however, great difference of 

 opinion as regards the origin of the vasa recta. In our opinion they 

 partake partly of the arterial, partly of the venous nature ; but in many, 

 though not the greater number of cases, more of the latter than of the 

 former springing from the capillary network of the cortical substance (fig. 

 527,/). 



They are joined then by the vasa efferenfia of the deeply-seated glome- 

 ruli (fig. 522, g ; 527, e, /, &), which possibly constitute their most 

 important source of supply. 



The number of arterial twigs, on the other hand, is quite inconsider- 

 able as far as we have ourselves observed, which are given off from the 

 branches bearing the glomerules, but before the latter are formed, and which 

 sink as arteriolae rectae into the vascular portion of the medulla (fig. 

 522, h; 528, /). 



As we have already remarked, the subdivision of stronger trunks to 



