If Mr. Simon's account of these cysts were correct they would be in fact hydatid cysts. I am not prepared to deny that cysts are ever formed in the kidney by the development of isolated cells, as described by Mr. Simon ; it is very possible that such an occurrence may be not unfrequent, although it has hitherto escaped my observation. But there can, I think, be no doubt in the mind of any one who will carefully examine the subject, that the appearances described and figured by Mr. Simon are produced simply by the packing of the tubes in the fibrous net work which surrounds and partially conceals them. The best safeguard against a misin terpretation of appearances in diseased speci mens is a careful study of the healthy tissues. The peculiar cyst-like appearance of the tubes in cases of chronic nephritis results from the transparency of the tubes when deprived of their epithelial lining. This delicate and transparent appearance of the tubes, which in the human kidney is the result of disease, may constantly be seen in the kidneys of some of the smaller animals ; as, for example, those of a mouse or a young rabbit. On examining thin sections of the kidneys of these animals it will be found that the delicate and semitransparent tubes, embedded in the surrounding fibrous network, constantly pre sent more or less of the cyst-like appearance represented in fig. 171. It can scarcely be supposed that these appearances in the kidney of the mouse indicate the existence of isolated cells. In short, Mr. Simon's theory of renal cysts is so opposed to all analogy-, and so en tirely unsupported by facts, that it appears needless to occupy the time of our readers by a further detail of facts and arguments in opposition to it.
Renal Hcemorrhage. — Under this head I will allude in a few words to a condition of kidney which I have never had an opportu tunity of examining in the dead subject, but the nature of which is sufficiently manifested by the sytnptoms, and particularly by the con dition of the urine, as ascertained by a micro scopical examination during life. It is well known that great irritation of the urinary organs is a frequent consequence of the inter, nal administration of oil of turpentine, or the application of cantharides to the cutaneous surface. The urine in these cases is generally bloody, and is passed very frequently and in small quantities ; there is great pain and irri tation about the kidneys and bladder ; but there are no symptoms of suppression of urine, such as drowsiness and tendency to in flammation of internal organs, symptoms which are present, in a greater or less degree, in all cases of " desquamative nephritis." In the last-mentioned cases the epithelial lining of the urinary tubes is the seat of disease, and the imperfect elimination of the solid consti tuents of the urine is a necessary consequence of the pathological changes which the secret ing epithelium undergoes. In the condition
of kidney now under consideration the Mal pighian capillaries appear to be the only parts of the organ primarily affected. The irrita tion produced by the turpentine or the can. tharides leads to engorgement of the Malpig hian tufts, which commonly ends in rupture of the vessels, hmmorrhage into the tubes, and so the admixture of blood with the urine. On a microscopical examination of the urine fibrinous moulds of the tubes may be seen in great numbers (fig. 175), blood corpuscles are entangled in the fibrine, but no epithelium is found combined with them. The inference is, that the epithelial lining of the urinary tubules is unaffected, and this conclusion is further supported by the fact already men tioned, viz,, the absence of the usual symp toms resulting from a deficient excretion of urea and the other solid constituents of the urine. I have never seen a fatal case of strangury ; but when hmmorrhage from the Malpighian capillaries has occurred in con nection with other pathological conditions which have terminated fatally, heemorrhagic spots are seen scattered over the surface and through the cortical substance of the kidney.
These spots, when submitted to a microsco pical examination, are found to be composed of convoluted tubes filled with blood which has escaped from the Malpighian capillaries, and after filling the capsule has passed into the tube (fig. 176). This fact was first pointed out by Mr. Bowman.
The condition of kidney to which turpen tine and cantharides give rise may result from the irritation produced by certain products developed within the body. I have met with two well marked cases of' this kind, in which the characters of the urine, as revealed by a microscopical examination, and the other at tendant symptoms were the same. In both cases the symptoms were of short duration. When the blood in cases of hmmaturia is found to be moulded in the urinary tubes, there can of course be no doubt as to the hemorrhage being renal. During the first few hours of an attack of hmmaturia it com monly happens that the blood escapes from the kidney before it has coagulated, and at this period of the attack a large quantity of the blood will be found not to have the form of cylindrical moulds when examined by the microscope, but even in this case a careful examination will always detect some moulds, and that will suffice for the diagnosis ; and at a later period of the attack, when the hmmor rhage occurs more slowly it will be found that nearly all the blood has been moulded into the urinary tubes before it has escaped from the kidney. When renal hmrnorrhage is pro duced by the irritation of a calculus impacted in the pelvis or the ureter, the blood does not present the fibrinous moulds in question.