THE URINARY ORGANS. 



597 



Fig. 245. 



course, but this becomes much more manifest in the cortical substance, 

 where they constitute the convoluted uriniferous tubules (tubuli contorti 

 s. corticales), which at first sight, appear to be inextricably and irregu- 

 larly interwoven, each terminating, ulti- 

 mately, as Bowman discovered in the 

 year 1842, in a vesicular, dilated ex- 

 tremity, 0-06-0-01 of a line in dia- 

 meter, containing a vascular plexus of 

 a peculiar kind the so-called Mal- 

 pighian body. Upon more minute ob- 

 servation, however, it is easy to perceive 

 the convoluted tubuli are arranged in 

 columnar masses, JJ of a line wide, 

 extending through the entire thick- 

 ness of the cortical substance and in 

 close apposition, which, notwithstand- 

 ing their incomplete limitation from 

 each other, may nevertheless be desig- 

 nated fasciculi corticales, or lobuli re- 

 num (or the "pyramids of Ferrein" of 

 the older anatomists). In these co- 

 lumns (Fig. 245), the tubuli uriniferi 

 are disposed, in miniature, in the same 

 way as in a renal lobe, so that in their 

 interior, more especially at the peri- 

 phery, convoluted canals may be dis- 

 tinguished. When the arrangement of 

 these parts is accurately investigated, 

 it is seen that the ducts of Bellini, en- 

 tering a cortical lobule in a fascicular 

 manner, at first run in perfectly straight 

 lines (Fig. 245 o). Soon, however, 

 some, and further on, more and more, 

 of the canals are curved laterally (Fig. 

 245 ra), in order to reach, in a ser- 



m 



FIG. 245. Vertical section through a portion of a pyramid and the cortical substance 

 belonging to it, of an injected Rabbit's kidney. The figure is half-diagrammatic ; magnified 

 30 cliam. The vessels are rspresented on the left side, and on the right the course of the 

 tubuli uriniferi : a, arteries interlobulares, with the glomcruli Malpighiani, 6, and their vasa cffe- 

 rentia : c, vasa efferentia ; d, cortical capillaries ; e. vasa efferentia of the outermost corpuscles, 

 proceeding to the superficial capillaries ; /, vasa efferentia of the innermost glomeruli, continu- 

 ous with the arteriolce rectce, g g g ; h, capillaries of the pyramids which are formed out of 

 the latter ; i, a venula recta, commencing at the papilla ; k, commencement of a straight 

 canal at the papilla Z, divisions of the same ; m, convoluted tubules in the cortex, their whole 

 course not shown ; n, the same at the surface of the gland; o, their continuation in the 

 straight tubules of the cortex ;p, their connection with the Malpighian capsules. 



