ORGANS OF THE BODY. 



519 



271. 



Turning now to the cortical substance of the kidney, we find just as 

 peculiar and complex an arrangement of parts as in that portion we have 

 been considering. 



In vertical sections (fig. 512) we observe that it consists of tubes twist- 



Fig. 512. Vertical section through the cortical portion of the kidney 

 of the infant (half diagrammatic). A A, medullary processes; B, 

 true cortical substance; a, collecting tube of the medullary pro- 

 cess; 6, finer tubes of the latter; c, convoluted tubes of the cor- 

 tical substance; rf, peripheral layer of the latter; e, an arterial 

 twig; /, glomeruli; g, transition of uriniferous tube into one of 

 Bowman's capsules ; h, envelope of th kidney with its lymphatic 

 interstices. 



ing and intertwining in all directions (B} ; but that, besides these, it is 

 traversed from within outwards by cylindrical bundles (A) of about 

 0-2707-0*3158 mm. in diameter, at regular and short intervals. These 

 bundles or cords are made up of canals of different calibre, which, in 

 some instances, become narrowed in their course outwards, where they 

 are lost in convolutions immediately under the surface, forming there a 

 narrow stratum of convoluted tubes (d). This cortical stratum of convo- 

 luted elements, consequently, is interrupted at intervals by the bundles 

 of straight uriniferous tubes (fig. 512, A), in about the same way that a 

 board is pierced by groups of closely-standing nails driven through it. 



These bundles, although discovered long ago, have only very recently 

 received particular attention. They have been given by Henle the name 

 of "pyramid processes" and by Ludwig that of " medullary radii'' 

 34 



