AMYLOID DEGENERATION OF THE KIDNEYS. . 423 



seen within the medullary cones, lying very close to one 

 another. These are all arteries. The affection of the 

 arteries becomes sometimes so severe, that, after the 

 application of the test, a clear view of the whole course 

 of the vessels is obtained, as if one had a very complete 

 artificial injection before one. But in these very kid- 

 neys an injection is hardly practicable. Even the finer 

 materials which we employ as injections, are much too 

 coarse to be able to pass through the narrowed vessels. 

 Upon examining one of these glomeruli microscopically, 

 we see that from the point, where the afferent artery 

 breaks up, the loops are no longer the fine, delicate 

 tubes that they formerly were ; on the contrary they 

 appear compact and nearly solid. Now as these are 

 just the parts which manifestly constitute the real 

 points at which the secretion of the fluid portion of the 

 urine is effected, we can easily conceive that in such 

 cases disturbances in the secretion of urine must arise. 

 Unfortunately we have as yet no completely satisfactory 

 analyses, but it seems that many cases of albuminu- 

 ria, which are attended with a considerable diminution 

 in the secretion of urea, are connected with these very 

 conditions, and that the excretion becomes more and 

 more scanty in proportion as tlie disease increases in 

 intensity.* These cases are very frequently complicated 



* This is what we might expect to take place, wherever we suppose the urea to 

 be secreted. If it is secreted by the epithelium, the epithelium must take it up 

 out of the blood which circulates in the intertubular capillaries. But if the glo- 

 meruli only allow a small quantity of blood to pass through them, a small quantity 

 only finds its way into these capillaries, and so but little urea cau be taken up and 

 excreted. In those cases in which there is an abundant flow of watery urine, the 

 water is chiefly derived from the vessels of the medullary substance, in conse- 

 quence of the increased (collateral) pressure upon them. Thus the amyloid de- 

 generation of the Malpighian bodies and their afferent arteries has much less 

 influence upon the excretion of water, than upon that of urea. The peculiar views 

 first put forward by the Author concerning the circulation in the medullary sub- 

 stance of the kidney, and the common origin (from the same branches of the 

 renal artery) of the arterise rectae of the medullary cones (pyramids), and of the 



