THE URINARY ORGANS. 195 



for. At the same time, towards the base of the pyramids, the 

 connexion of the ducts of Bellini is rendered less close, by the 

 interpolation between them, at regular distances, of large vas- 

 cular bundles (arteriole and venulce recta), and they become 

 separated on all sides from each other, so that, in perpendicular 

 sections, the pyramids (the papilla of course excepted) in the 

 entire circumference appear to spread out into numerous small 

 bundles or pencils — the pyramids of Ferrein of authors — but 

 which, as sections across them show, are only to be regarded as 

 separate, sharply-defined fasciculi. The tubuli uriniferi, even 

 here, assume a slightly undulating course, but this becomes 

 much more manifest in the cortical substance, where they con- 

 stitute the convoluted uriniferous tubules (tubuli contorti s. cor- 

 ticales), which, at first sight, appear to be inextricably and irre- 

 gularly interwoven, each terminating, ultimately, as Bowman 

 discovered in the year 1842, in a vesicular, dilated extremity, 

 0*06 — 0-01'" in diameter, containing Tt vascular plexus of a 

 peculiar kind — the so-called Malpighian body. Upon more 

 minute observation, however, it is easy to perceive that the 

 convoluted tubuli are arranged in columnar masses, \ — ff" wide, 

 extending through the entire thickness of the cortical sub- 

 stance and in close apposition, which, notwithstanding their 

 incomplete limitation from each other, may nevertheless be 

 designated fasciculi corticales, or lobuli renum (or the "pyramids 

 of Ferrein" of the older anatomists). In these columns (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 periphery, convoluted canals may be distinguished. 

 When the arrangement of these parts is accurately investigated, 

 it is seen that the ducts of Bellini, entering 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 m), in order 

 to reach, in a serpentine course, the arterial twigs surrounding 

 the cortical lobules ; until, at last, the entire bundle of tubules 

 is broken up, at some distance from the surface of the kidney 

 (or of the centre of the column® Bertini), into convoluted 

 canaliculi. The Malpighian bodies (fig. 245 b), from which 

 the tubuli uriniferi arise, are found throughout the entire 

 thickness of the cortical substance, from the pyramids to within 



