598 SPECIAL HISTOLOGY. 



pentine 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 columnce Bertini\ 

 into convoluted canaliculi. The Malpighian bodies (Fig. 245 5), from 

 which the tiibuli uriniferi arise, are found throughout the entire thick- 

 ness of the cortical substance, from the pyramids to within 5^ of a line 

 from the surface, as well as in the septa Bertini, down to the sinus of 

 the kidney and are disposed so regularly and in such numbers, around 

 the cortical lobules, that every transverse section through the cortex 

 always displays a red streak, caused by these corpuscles, between each 

 two lobules. Usually each of these streaks consists of a minute artery, 

 with from two to four, of Malpighian bodies supported by it, but not in 

 regular series, some of which stand more in relation with the one, and 

 others with the other cortical bundle. Each fasciculus of tubuli urini- 

 feri, therefore, upon entering the cortical substance, is, from the first 

 entirely encompassed by the Malpighian bodies, and it is obvious that 

 some of the tubuli quit it soon and others later, in order to reach their 

 appropriate Malpighian bodies.* For the rest, each corticaf tubule, after 

 its origin, is much convoluted, runs at first somewhat outwardly, and 

 then returns upon itself, to join the straight tubules of the cortical 

 fasciculus. 



The number of the convoluted tubuli uriniferi corresponds with that 

 of the Malpighian bodies and is consequently, in every instance, very 

 considerable. According to Huschke, 200 tubuli exist in each fasciculus 

 corticalis, and 700 such fasciculi in a pyramid ; which calculation gives, 

 in fifteen pyramids, more than two millions of commencements of tubuli 

 and Malpighian bodies. Since each papilla has about 500 or even more 

 orifices, it is possible that each cortical fasciculus proceeds from a single 

 " duct of Bellini ;" in any case, it is evident that in every straight 

 tubule the divisions are repeated at least ten times.* 



v 188. The tubuli uriniferi, are everywhere composed of the same 

 elements ; viz. of a membrana propria, and a tessellated epithelium. The 

 former is a perfectly structureless, transparent, thin (0-0004-0-0008 

 of a line), but proportionately strong and elastic coat, which, particu- 

 larly in the straight tubules, may be very easily isolated for a considera- 

 ble extent, when it is very prone to fall into folds, which often present 

 the striated aspect of connective tissue. On the inner surface of this 



* [It would scarcely be deduced, from what is said in the text, that the tubuli uriniferi, in 

 the cortical part of the kidney, anastomose very freely and frequently, although the fact of 

 their doing so has been long well known and often described. These anastomoses, how- 

 ever, and the general disposition of the tubules, are more particularly adverted to and well 

 depicted by Toynbee ( ;i Med. Chir. Transact.," 2d ser., vol. XI. p. 308, pi. 7). TRS.] 



