488 



KIDNEY. 



[CHAP, xxxiv. 



Fig. 232. 



been proved in several ways. In specimens which have been 

 carefully injected from the artery, not nnfrequently it will be found 

 that the coloured material escapes and extravasates from the vessels 

 of the tuft into the cavity of the capsule, and thence runs down 

 the tube (Fig. 231). 



In disease, it is not at all uncommon to find the capsule of the 

 tuft, and the tube itself, injected with blood, in consequence of 

 haemorrhage from the vessels of the tuft. 



The difficulty of injecting the capsule by forcing injection from 

 the pelvis of the kidney, cannot reasonably be urged as an objec- 



tion to this view, for all who 

 have had any experience in in- 

 jecting the minute ducts of 

 glands, will agree that it is in 

 very few instances indeed that 

 the injection can be forced to 

 the termination of the tube. 

 The epithelium within it is apt 

 to be forced towards its csecal 

 extremity, and by its accumu- 

 lation renders such a result 

 impossible, while, in the ma- 

 jority of cases, the force requi- 

 site to overcome the resistance 

 to the passage of fluid, along a 

 highly convoluted tube in the 

 reverse direction to that which 



Malpighian tuft ; kidney of the Protens anguineus, its Contents naturally take, IS 

 showing vessels lying within the capsule, the inner . 



surface of which is entirely covered with a single more than Sufficient to CaUSC its 



tube. 



layer of tesselated epithelium, a. Uriniferous tu 



b. Capsule, c. Tuft of vessels which were injected in rupture. 



the preparation from which this drawing was taken. * 



a/. Terminal twig of the artery, ef. Efferent vessel. 



Magnified about 50 diameters. A small portion of the 



capsule, with its epithelial lining, is represented in 



the smaller figure, magnified 215 diameters. 



-, i PIT 



TllC Kidney OI the horse IS 



., , , , 



VCrV taVOUrable tor demon- 



* . . . -, , 



stratmg these points, and the 

 double injection, composed of acetate of lead and bichromate of 

 potash, will be found to furnish the most satisfactory results. 



In the kidney of the frog, or of the newt, the continuity of the 

 capsule with the basement membrane of the tube is exceedingly 

 distinct and easy of demonstration. The tuft of vessels is seen 

 lying naked within the capsule, uncovered either with epithelium 

 or by any reflection of the basement membrane composing the 

 capsule. In the frog, the neck of the tube close to and some way 

 within the capsule is lined with ciliated epithelium, which con- 



