1 66 



SIXTEENTH LECTURE. 



tracted transition into the uriniferous canals (the so-called 

 neck) was discovered at a relatively recent period. 



Only the most external cortical portion of our organ (Hyrtl 

 named it the cortex corticis) is without this peculiar vascular 

 coil (Fig. 150, d\ Fig. 155, d). 



The inner surface of this capsule has a lining of large, fiat, 

 endothelial cells. 



The external surface of the glomerulus presents an invest- 

 ment of smaller cells which are not so flat. I found them 

 thus, formerly. According to Heidenhain, however, the lat- 

 ter elements are likewise quite flat. 



In the convoluted uriniferous canals we meet with a clouded, 

 granular, cubical epithelium, and the lumen is quite narrow. 

 Following this glandular tubule downwards, we find it as- 

 suming a straight and direct course. At first it still remains 



wide, and the gland cells are 

 unchanged. Then, having en- 

 tered the medullary substance, 

 it diminishes in width, exceed- 

 ingly, and now becomes the 

 narrow descending side of 

 Henle's looped canal. A re- 

 markable transformation of the 

 epithelial lining has taken 

 place at the same time ; quite 

 thin, flat scales, appearing like 

 vascular endothelium, now 

 line the canal (Fig. 152, #.) 

 Following the loop further, 

 we arrive at the ascending 

 wider side. Its epithelium is 

 again the old, clouded, glandular variety of the convoluted 

 uriniferous canals, as we must maintain in contradistinction 

 to Ludwig. 



The returning side finally passes over in the cortex — some- 

 times deeper, sometimes quite near the surface — into an 

 expanded, gut-like convoluted structure, the so-called " inter- 



I ig. 153. — From the kidney of the pig (scmi- 

 diagramatic) ; «, arterial branch : b. afferent 

 vessels of the glomerulus, c ; d, vas efferens ; 

 e, breaking up of the same into the straight 

 capillary plexus of the medullary ray ; _/, 

 rounded plexus of the convoluted canals ; /', ,f, 

 commencement of the venous branch. 



