FIG. 6.-Section of Kidney about the base of Pyramid. In the centre is seen a mass composed of a central group of Micrococci, surrounding this the clear necrotic area, and outside the, inflammatory zone, consisting of a number of Leucocytes. x 44.

FIG. 7.-A mass similar to that shown in Fig. 6, more highly magnified. Here the central plug of Micrococci and the necrotic and inflammatory rings are well shown. Part of central mass of Micrococci has fallen out.

x 80.

FIG. 8. In the corner is seen the same appearance as above; the central Micrococci, the Necrotic Area, and the Inflammatory Infiltration. In the centre is another mass, in which the necrotic area has disappeared, having been encroached on by the leucocytes. A group of Micrococci is still seen in the centre of the mass.

x 80.

FIG. 9.-One of the Masses seen in Figs. 6 and 7, more highly magnified. To the left is the mass of Micrococci; quite to the right the inflammatory ring, and intermediately the necrotic area, infiltrated with Micrococci. What are evidently remains of two Kidney-tubules are seen full of Micrococci and Leucocytes. x 375.

X 125.

FIG. 11.-Section of Kidney, showing Tubule cut across containing Micrococci adhering to the surface of the Epithelial Cells (the cut is not at all a successful representation of the photograph). X 750.

but the epithelium has not yet become necrotic. (See figs. 11 and 12.) The mode of origin of these plugs in the urinary tubules is evidently the following. Micrococci are either excreted by the kidney somewhere in the cortex, or escape into the tubules from the plugs in the cortex previously alluded to. Being carried along by the urine, they grow and adhere at parts to the epithelium along the canals, as shown in the accompanying drawing, which is an accurate copy of a microphotograph. (See fig. 12.) They soon fill the canal, and cause necrosis of the epithelium and the surrounding tissue, and the further changes which have just been described. In the pyramid, they soon grow out of the tubule, and spread in the surrounding tissue, in the form of a network, between the tubules.

immediate vicinity, so that it does not take on the stain; and thus the intensely stained mass is surrounded by a clear necrotic ring. Outside this ring, there is another ring of inflammatory infiltration. (See figs. 6, 7 and 8.) After a time, the micrococci spread from the central mass into the clearing around, the central mass becoming also less dense. (See fig. 9.) At the same time, the leucocytes spread from the outer ring into the clear ring; (see fig. 8) and, ultimately, the central mass of organisms is completely broken up, and we have a collection of leucocytes, among which are numerous micrococci. Here, apparently, the process ceases, and retrogression occurs; the micrococci disappear; the cells become absorbed, or organise into fibrous tissue; and thus, in the kidneys of the rabbits which died on the ninth and 14th days-more especially I have said that the micrococci gained enin the latter-we only find patches of organis- trance to the tubules probably in two ways. ing inflammatory tissue without micrococci. That they might have penetrated from the in(See fig. 10.) If, now, we look at the ones flammatory masses in the cortex, was often which died on the second and third days, we shown by the presence in several instances of find that, in the more superficial masses, there leucocytes as well as micrococci in the tubules, is already, in some instances, considerable in- more especially in the tubules in the neighborfiltration of the clear area with leucocytes; in hood of the masses. On the other hand, I some, there is complete infiltration up to the have found small groups of micrococci alone in central plug of organisms; and, in a few, the tubules in the cortex, without the presence of central plug has disappeared, and we have a any plugs from which they could have come. mass of leucocytes, with micrococci lying (In connection with this matter, it is interestamong the cells. The latter masses are, there-ing to note that, there were never any plugs in. fore, the oldest. On the other hand, the masses or affection of, the glomeruli.) These facts towards the apex of the pyramid are in many would seem to point to the kidney as an imcases only surrounded by a clear ring; in portant excreting organ for micro-organisms. some, there is also the inflammatory ring out- Dr. Ogston, in fact, mentions in his paper that side, but the cells have not yet penetrated into he has found micrococci in the urine of man in the clear space. These masses are, therefore, cases where acute inflammatory processes have of later formation than the former. The ap- been going on, without there being any reason pearance of the sections, even under a low for supposing any lesion of the kidneys. power, at once raise the question, whether the masses of micrococci are in the blood-vessels or in the urinary tubules. This question is not easily decided, on account of the rapid necrosis of the cells immediately surrounding the mass. Where this necrosis is complete, in the immediate vicinity of the mass, the epithelium of the tubules, and indeed all the tissue around, remain unstained, and partially invisible. I have, however, after careful study of numerous sections, convinced myself that by far the greater majority of the masses are, in the urinary tubules. This is especially the case in the pyramid; while, with regard to the masses of earlier formation, it is possible that some are in blood-vessels. In the neighborhood of the large masses, I have got many specimens where, in a transverse section of a tubule, and also in some longitudinal sections of tubules, there are small masses of micro- ! cocci, not filling up the interior; while, in other cases, the calibre is completely filled up,

It is of interest to note that the injection of a large quantity of these organisms was necessary to produce a fatal effect; as the quantity was reduced, the length of time before death was increased. (The only real exception to this is in the case of the injection with micrococci growing in carbonic acid gas, but carbonic acid seems to retard and injure the growth of some micro-organisms more than would be the case if they were merely deprived of oxygen.) The organism had thus little power of growing in the blood; and the fatal result is attributable to the disorganisation of the kidney from the growth of the organisms in the tubules after being excreted, and also probably from the absorption of the ptomaines formed by them when growing in the kidney, and which exercised a deleterious effect on the surrounding tissues.

SERIES V. The micrococci were obtained from a case of excision of the mamma and axillary glands, which was hardly following a