frayed and shreddy. In animal fibers, the latter denotes shoddy; in vegetable, paper. Now with a glass rod or medicine dropper allow a little iodine to flow under the cover and the fibers will soon assume a clear light brown. Any surplus should be absorbed by a piece of blotting paper, for with reasonable care there is not the least necessity for soiling the stage of your instrument. As soon as the iodine has penetrated apply the sulphuric acid in the same way, and carefully watch the result, comparing it with the annexed table. Several minutes will sometimes elapse before the coloration is complete, and it does not endure for more than a few hours. Bent or creased fibers color more deeply in the flexures, and striæ, either longitudinal or radial (in sections) will show more plainly as the coloration progresses. In many sorts, of coarser fibers especially, pieces of parenchyma will be seen, that always color yellow, and may readily be known by their irregular shape. Cross sections can be made with any section cutter by gluing together a little mass of fibers, or bedding them in paraffine, or as often practiced by the writer, rolling them somewhat like a cigarette in a piece of sheet wax such as is used for wax flowers. When cut the mass of mixed sections is placed in benzole or alcohol, when the wax soon floats on top and may be poured off. We owe to Vetillart the classification adopted above, which is an important analysis of the reactions of cellulose. The observations in the last column indicate only the prominent characters of each fiber. Mirbel called fiber cells bast cells, a name still used. In Dicotyledons they form the inner layer of the bark, are usually more or less colored, long, supple, and tenacious; in Monocotyledons they are scattered irregularly through the stem, are white, coarse, light, and often brittle. The central cavity and shape of the ends of the cells are important features. The blue reaction of Monocotyledons is not so uniform as that of the other classes, quite a large proportion of alfa and esparto also turning yellow; there being apparently two distinct kinds of cells in these plants, which are not mixed indiscriminately in the stem but form separate layers, each of which maintains its characteristic reaction, but becomes intermixed in processes of manufacture. An inspection of the column headed ratio, will show at once why certain fibers maintain so prominent a place in the indus try of the world. These figures arranged in order of magnitude nearly represent commercial value for textile fabrics, but for paper stock other conditions modify the result. EMIGRATION IN PASSIVE HYPERÆMIA. BY W. T. BELfield, m. d., OF CHICAGO.* In March last I had occasion to superintend the post mortem examination of a case of pneumonia, in which death had occurred on the tenth day of the disease. There was found consolidation of the entire left lung, gray hepatization in the lower lobe, red in the upper. Nothing peculiar was noticed in the other organs except general engorgement, especially marked in the kidneys. There had been during our observation of the patient not a solitary symptom of renal disease except the presence of albumen (about 5%) in the urine-a presence known to be common in pneumonia, and attributed to mechanical congestion. For at least three features of pneumonia tend to the production of mechanical congestion, namely: the decrease in breathing surface, the increase in the demand for oxygen made by the excessive tissue change, and the feebleness of the heart's contractions. Hence the albuminuria and the post mortem engorgement of the kidneys were regarded as legitimate results of the disease. A happy curiosity, however, led me to make a microscopical section of the kidney. I found the tubules rather smaller than usual, the intertubular spaces and capsules of the malpighian tufts much thickened by the presence within them of numerous small, round, finely granular cells to inch in diameter. These cells had every appearance of white blood corpuscles, and were so pronounced by Dr. Danforth and others. By way of explanation it was presumed that the retardation of the blood current, due to the causes previously mentioned, had afforded the colorless corpuscles an opportunity to exhibit their amoeboid movements -and that the opportunity had been improved. That this was not an inflammatory process, was proved by the absence from the clinical history of all the recognized symptoms of renal inflammation, and by the absence from the urine of the * Read before the National Microscopical Congress at Indianapolis, August 16th, 1878. 1 exudation cylinders or tube-casts. Nor were the microscopic appearances of the organ those of inflammation. Within six weeks I had an opportunity of examining the kidneys of two other patients dead from pneumonia, without previous history of renal disease. In each case the urine contained a small quantity of albumen, but no casts, and in each instance colorless corpuscles were found in abundance in the intertubular tissue, and in the malpighian capsules. At a meeting of the West Chicago Medical Society, held June 10th, I exhibited a section from one of these kidneys, and another from a normal kidney, demonstrating to the satisfaction of those present the existence within the connective tissue of the former organ of the small round cells above described. At that time I had sought unsuccessfully for literature or a reference to literature on this subject. However, deeming the fact, if it were a fact, of the migration of leucocytes in passive hyperæmia a very important one pathologically, I determined to investigate the case, and for that purpose instituted the proceedings about to be narrated. On June 19th, I curarized a frog, cut down on the femoral vein (which can readily be done without injuring the artery, as in this animal the vein and artery lie on opposite sides of the femur), made compression by means of a rubber band and a plug of cork, and stretched the web of the corresponding foot on the stage of the microscope. I employed a Hartnack No. 4 objective, and a Grundlach C periscopic eyepiece. By watching the blood movements I easily regulated the pressure so as to retard more or less completely the onward movement, avoiding complete stagnation. After considerable compression had been exerted, as was shown by accumulation of blood corpuscles, distension of the vein, and retardation of the current, the field was carefully watched for nine hours. During that time no leucocytes were actually observed to leave the vessels, yet several were seen just external to the walls, having apparently escaped unnoticed during the shifting of the stage. For the next ten hours the field was not observed with sufficient care and frequency to warrant any assertion of migration. At the end of this period, however, that is, nineteen hours after compression was made, an almost continuous observation of the field was begun. From the 19th to the 36th hour leucocytes were observed to leave the vessels in considerable num bers, the shortest time of exit observed being twenty minutes -the average one to two hours. The method of locomotion did not, of course, differ from that exhibited in inflammation, though at no time did I observe the excessive change of form and protrusion of long processes figured in the books. There was frequently a flattening of the leucocyte against the wall; then the appearance of a bud external to the wall; then the gradual enlargement of this bud and shrinkage of the intravascular portion, the part piercing the wall being apparently a tunnel through which the rest of its body passed. Often the locomotion was continued after the leucocyte had become wholly extra-vascular, so that it traveled several times its own diameter from the place of exit. It was noticed, too, that other corpuscles were prone to pass out at the particular point of previous migration, so that sometimes several would be crowded together along the vascular wall, and an hour later would be in close proximity, external to the vessel opposite the same point. 600 This phenomenon occurred usually not in the minutest capillaries but rather in the large capillaries and small veins, ranging from to inch in diameter. Nor were the passages always made where the current was slowest, nor where the vessel gave evidence of greatest engorgement-by the crowding of the corpuscles—as emigration from a rapid current but sparsely supplied with corpuscles was not infrequent. Before I had watched the process a great while I became aware that the colorless corpuscles were not the only bodies exhibiting amoeboid movements. I observed that certain red ones without nuclei, of circular shape and small size (inch in diameter), performed the same movements with as great celerity as did the white. (The listener is reminded that in the frog the perfect red corpuscle is of elliptical shape, is inch in its longer diameter, and has a distinct nucleus; while the white globule is, when at rest, of circular shape, its diameter only about inch.) There could be no possibility of confounding these small red ones with the white, for although in size, shape, and movements, they were identical, the red color of some was unmistakable. So extensive was the locomotion of the red ones that at the 36th hour of the experiment there were numerous red patches in the field, which looked almost like hemorrhages. That they were not hemorrhages I knew, |