Points in the Histology of the Human Kidney. 165 



present such an appearance, more or less exactly as it is given in 

 the pretty and complete pictures which pass for illustrations of 

 renal tissue in the books on the subject. 



It might be asked, Why should the hardening and contracting 

 effect of alcohol on the epithelium of the tubule have the appearance 

 of a central canal as a consequence, and not rather a breaking up 

 into irregular forms ? The best answer to such a query would be 

 to point to the facts as already indicated. But if a reason must 

 needs be furnished, it would be easy to find one in the circumstance 

 that the epithelial tissue next the basement membrane is younger, 

 nearer the sources of nourishment, more vigorous therefore and 

 able to maintain its cohesion ; whilst to that in the centre the con- 

 trary conditions apply, and hence in contracting it is this portion 

 which must yield. It follows also as a consequence of the chcular 

 character of the tubule, that its contents will contract equally 

 towards the circumference, leaving an empty ring in the centre. 



It is clear therefore that the kidney has hitherto been made 

 the victim, so to say, of the very means employed for its elucida- 

 tion ; for while on the one hand the current descriptions abound 

 with new and manufactured appearances, on the other it is unusually 

 liable to the errors which, as above pointed out, but too frequently 

 ensue from the substitution of the organs of the lower animals. 



To return to the actual description before us, it will be remem- 

 bered that the more recent investigators are agreed that there is at 

 least a cellular element in the composition of the malpighian body. 

 Thus some consider the capsule to be lined with cells ; and others 

 state in addition that there is a layer of cells covering the vessels ; 

 the main feature, however, of Bowman's idea, that the organ is 

 made up of a tuft of vessels enclosed in a capsule, being still held 

 good by every writer. 



In opposition to the views of Bowman, as also to those of more 

 recent date, it has been already seen, that I venture to assume and 

 maintain the malpighian body to be primarily and essentially 

 cellular, and that its vessels are secondary and subordinate ; that 

 the ceU structure is not limited to the lining of the capsule and 

 the covering of the tuft of vessels, but that it composes the bulk 

 and corpus of the organ, and that the vessels instead of being free 

 and independent, ramify in the mass of cells and contribute to their 

 function ; much in the same way in fact as the main principle of 

 the liver lobule is cellular, while an especial system of vessels is 

 necessary to its office. 



The very simple proof of this proposition is, that at whatever 

 angle the glomerulus is cut through, or whatever segment of it 

 may be removed, the portion remaining invariably shows the same 

 cell structure. In a thin section of the uninjected and otherwise 

 unmanipulated and uninjured kidney these bodies are necessarily 



