444 THE KIDNEYS AND THEIR SECRETION. 



organ chiefly in the intervals between the papilla), and 

 penetrate the cortical substance, where this dips down 

 between the bases of the pyramids. Here they form a 

 tolerably dense plexus of an arched form, and from this 

 are given off smaller arteries which ultimately supply the 

 Malpighian bodies. 



Fly. 124.* The small afferent artery (fig, 



124), which enters the Malpi- 

 ghian body by perforating the 

 capsule, breaks up in the interior 

 into a dense and convoluted and 

 looped capillary plexus, which is 

 ultimately gathered up again 

 into a single small efferent vessel, 

 comparable to a minute vein, 

 which leaves the Malpighian 

 capsule just by the point at 



which the afferent artery enters it. On leaving, it does 

 not immediately join other small veins as might have been 

 expected, but again breaking up into a network of capil- 

 lary vessels, is distributed on the exterior of the tubule, 

 from whose dilated end it had just emerged. After this 

 second breaking up it is finally collected into a small vein, 

 which, by union with others like it, helps to form the 

 radicles of the renal vein. 



The Malpighian capsule is lined by a layer of fine squa- 

 mous epithelial cells; but whether the small glomerulus 

 or tuft of capillaries in the interior is covered by a similar 

 layer is uncertain. Kolliker believes that such a covering, 



* Fig. 124. Diagram showing the relation of the Malpighian body 

 to the uriuiferous ducts and blood-vessels (after Bowman) : a, one of 

 the interlobular arteries ; a', afferent artery passing into the glomerulus ; 

 c, capsule of the Malpighian body, forming the termination of and con- 

 tinuous with t, the uriniferous tube ; c r , c', efferent vessels which sub- 

 divide in the plexus p t surrounding the tube, and finally terminate in 

 the branch of the renal vein e. 



