194 



SPECIAL HISTOLOGY. 



Fig. 245. 



uriniferi), cylindrical tubules, measuring, on the average, 0016 



— 0-025"'. They commence in 

 each renal lobe or segment, in 

 those portions of the pyramids 

 which are surrounded by the 

 calices renales, or on the renal 

 papillae, by, on the average, 

 from 200 to 500 orifices, 0*024 

 — 1'" wide, scattered over the 

 surface of those processes; they 

 traverse the pyramids in nearly 

 a straight line and in close con- 

 tiguity, whence they are termed, 

 in that situation, tubuli recti (or 

 Belliniani) (fig. 245 k). In this 

 course, each of the straight canals 

 divides repeatedly, most usually 

 under very acute angles and at 

 first with a considerable diminu- 

 tion of size, either into two (fig. 

 245 /), or more rarely into three 

 or four, so that, ultimately, a 

 complete bundle of finer tubules 

 is produced from them ; and in 

 this way the continued increase 

 in breadth of the pyramids to- 

 wards the exterior is accounted 



Fig. 245. Vertical section through a 

 portion of a pyramid and the cortical sub- 

 stance belonging to it, of an injected Rab- 

 bit's kidney. The figure is half-diagram- 

 matic ; x 30 diam. The vessels are represented on the left side, and on the right 

 the course of the tubuli uriniferi : a, arterice interlobular es, with the glomeruli 

 Malpighiani, b, and their vasa efferentia ; c, vasa efferent ia ; d, cortical capillaries; 

 e, vasa efferentia of the outermost corpuscles, proceeding to the superficial capil- 

 laries ; f, vasa efferentia of the innermost glomeruli, continuous with the arterioles 

 recta, g g g ; h, capillaries of the pyramids which are formed out of the latter ; i, a 

 venula recta, commencing at the papilla ; 7c, commencement of a straight canal at 

 the papilla; I, 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 continua. 

 tion in the straight tubules of the cortex ; p, their connexion with the Malpighian 

 capsules. 



