162 Points in the Histology of the Human Kidney. 



sisting in this way of a number of small looped vessels called the 

 malpighian tuft. 



According to this description the malpighian body consists of 

 two structures, and two only, viz. ^Bowman's capsule, and the free 

 tuft of vessels it encloses. But on section of the fresh and unmani- 

 pulated kidney, we have in fact in addition to these a third, forming 

 too the largest, most prominent, and most obvious feature of the 

 whole. This additional structure is composed of cells, and in ap- 

 pearance is hardly if at all distinguishable from the glandular epi- 

 thelium lining the convoluted tubes. Our section of the malpighian 

 glomerulus in short presents a picture, not simply of a capsule 

 containing vessels, but one composed mainly of a spherical-shaped 

 cellular body ; it is within the tissues of this body that the vessels 

 ramify and form their loops as described, whilst its surface is closely 

 invested by the so-called capsular membrane in question. 



The function of the malpighian body has been deduced from its 

 supposed simple structure ; and nothing could be more natural 

 than the idea that the tuft served, by a process of exosmosis, to 

 pour off the watery portion of the urine, whilst the capsule col- 

 lected and transmitted the same to the tubule in continuation with 

 it. But in presence of the above-described additional cellular body, 

 it is clear we have to seek anew the duty which must be assigned 

 to the organ ; the functional physiology, that is to say, of this 

 portion of the tissues of the kidney, together with its pathological 

 significance, have in fact yet to be discovered. 



The current descriptions of the convoluted tubuli uriniferi like 

 those of the malpighian body, would seem to require an almost 

 thorough revision. The accepted "view is, that the tube of base- 

 ment membrane is lined to not more than a third of its depth, by 

 glandular or secreting epithelium in the form of distinct cells; 

 leaving thus a central open canal for the passage of the secretion. 



It will be remarked that this central canal fits in well with 

 Bowman's idea of the function of the malpighian body, and perhaps 

 is essential to it. But upon any other ground than this, it would 

 be difficult to imagine how the conception originated ; for there is 

 nothing more certain than that no such canal can be seen ; on the 

 contrary, in the words of Ludwig, the " tube is filled by a pulpy 

 granular mass." Nor is it the fact that this mass has a defined 

 character of distinct cells ; it is emphatically an undifferentiated 

 though nucleated mass. 



It is true that Ludwig adds " this pulpy mass presents numerous 

 fissures, which however lie at very irregular distances"; and he 

 gives a figure exemphfying that view. These fissures will probably 

 be claimed as representing the central canal. 



I have not been able to verify the presence of these fissures; 

 and after much patient examination have come to the conclusion 



