THE KIDNEYS SECRETION OP URINE. 



491 



plexus formed by the tuhuli uriniferi seems to come into the closest relation 

 with that of the sanguiferous capillaries, so that it is probably the seat of 

 the greater part of the process of secretion ; whilst the latter is principally 



FIG. 17G. 



-, n Di \ t Iffliwmi '/#$ 

 : . c A , 4 ,.i t-T CT/,x '//; //?57/ / C^s 





Section of the Cortical Substance of the Human Kidney: A A, tubuli uriniferi divided transversely, 

 showing the spheroidal epithelium in their interior: B, Malpighian Capsule; a, its afferent branch of 

 the renal artery; 6, its glomerulus of capillaries ; c c, secreting plexus formed by its efferent vessels; 

 d (1, fibrous stroiua. 



composed of tubes, passing in a straight line from the former towards their 

 point of entrance into the ureter. The tubuli uriniferi, in passing out- 

 wards from the Calices, frequently divide in a dichotomous manner, thus 

 becoming greatly increased in number, whilst their diameter diminishes 



FIG. 178. 



FIG. 177. Portion of the Kidney of a new-born infant: A, natural size; 1, 1, Corpora Malpighiana, 

 as dispersed points in the cortical substance ; 2, papilla. B, a small part magnified ; 1, 1, Corpora Mal- 

 pighiana ; 2, tubuli uriniferi. 



FIG. 178. Portion of one of the Tubuli Uriniferi, from the medullary substance of the kidney of an 

 adult; showing its tessellated epithelium. 



from ^ to g-Jo of an inch. Each branch, as it is given off, first enlarges 

 and becomes tortuous, forming the intermediary portion of Ludwig, then 

 contracts and (b, Fig. 179) runs towards the apex of the pyramid in the 

 form of a very narrow tube, and after a course of variable length, loops back 

 (c c) towards the cortical portion, forming the loop of Henle, where it be- 

 comes wider and much convoluted, and terminates in a dilatation which has 



