212 SPECIAL HISTOLOGY. 



an increased secretion of the elements of the blood takes place 

 in the Malpighian bodies and tubuli uriniferi, in consequence of 

 which the epithelium of those parts, which, as is well known, is 

 found in these cases in considerable quantity in the urine, is 

 washed away, whence, of course, any further hinderance to the 

 continued passage of the above substances is removed. A 

 permeation of fibrin through the epithelium is also conceivable, 

 just as much, for instance, as upon the mucous membrane of the 

 respiratory organs, although I do not believe, that an increased 

 pressure of such a kind as to induce a transudation of fibrin 

 could fail to affect the delicate epithelium. When the epithe- 

 lium is once removed, it becomes an important question, 

 whether it is quickly restored ; and it appears to me, that the 

 frequent occurrence of small quantities of albuminous matter 

 in the urine, often depends simply upon local deficiencies of the 

 epithelium caused in one way or another. 



{.Investigation of the kidney. — The tubuli uriniferi are readily 

 isolated when the tissue of the organ is teased out ; the epithe- 

 lium, membrana propria and canal, being distinctly recognisable, 

 if blood-serum, or a solution of albumen be employed to 

 moisten it. Together with entire tubules, there will be found 

 in every preparation numerous epithelial cells, separate or in 

 groups, or even, as especially in the pyramids, in the form of 

 long continuous tubules. The latter often present a peculiar 

 aspect, for the most part collapsing, exhibiting somewhat 

 flattened cells and resembling vessels. Equally frequent, 

 are longer or shorter tubes of the membrana propria, which, 

 when much plicated, cannot always at once be recognised. In 

 the examination of the pyramids, the extremely numerous 

 vessels must not be confounded with the " ducts of Bellini," or 

 the epithelial casts that have escaped from them. The connexion 

 of the tubuli uriniferi with the Malpighian bodies, is easily 

 discerned in the kidney of the Frog and of Fishes, upon 

 careful teasing out of the structure ; but in Mammalia, also, it 

 will rarely be missed, in fine, hardened sections, and especially 

 in injected preparations. The glomeruli themselves may fre- 

 quently be recognised when naturally injected, and still better 

 when artificially filled, which we may very readily succeed in 

 doing with any fine material thrown in by the arteries. Similar 

 injections, also, when successful, fill the whole capillary plexus 



