1 64 



SIXTEENTH LECTURE. 



d — 



cortex from point to point, in the form of straight bundles (c). 

 They are here called medullary rays. Between them, al- 

 though incompletely demarcated, remain considerable portions 

 of the cortical substance (e), comparable to a truncated pyra- 

 mid. These are the so-called cortical 



(| P pyramids. In them run the glandular 



1 I 11 • 1 , -r , , 



tubules, with the most manifold turnings, 



which finally encompass, with their knob- 

 like dilatations, the Malpighian vascular 

 coil or glomerulus (Fig. 96). The latter 

 structures occur in this portion of the 

 organ only. 



Let us now commence the discussion 

 of the particulars with the most internal 

 division, with the apices of the medul- 

 lary pyramids, the renal papillae. Here, 

 alone, in the form of 10 to 15 apertures, 

 the efferent canal-work of this organ, 

 which is so complicated in its structure, 

 opens as a system of short canals (Fig. 

 151, a). Very soon afterwards they 

 break up, by acute-angled ramifications, 

 into branches of the first and second 

 order [b, c), and this is repeated several 

 times more. The whole thus acquires a 

 brush-like appearance. The canals be- 

 come narrowed, in consequence of this 

 continual subdivision, from 0.3 and 0.2 

 to 0.05 mm v About 4 to 5 mm. from 

 the apex of the papilla the process oi 

 division ceases, however ; the straight 

 canals now maintain their diameter un- 

 changed for a long distance. 



Between them — and this was dis- 

 covered by Henle — occurs an additional 

 system of much finer loop-shaped canals (d). In order to 

 facilitate a further insight, let us give to that particular part 



Fig. 151. — Vertical section 

 through the medullary pyra- 

 mids of the pig's kidney (semi- 

 diagramatic) ; a, trunk of a 

 uriniferous canal, opening at 

 the apex of the pyramid ; b 

 and c, its system of' branches ; 

 d, loop-shaped uriniferous ca- 

 nals ; e, vascular loop, andyj 

 ramification of the vasa recta. 



