IN a recent publication 2 we discussed certain strings oj granules which can be found by means of appropriate stain. ing in a percentage of the red corpuscles in health and disease. We showed that they are the remains of the nucleus of the original cell and called them chromolinin granulations. In health they occur roughly in about 1 per cent. of the cor. puscles, but in a few pathological conditions which we studied they occurred much more frequently. Thus, in a case of tropical abscess of the

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... liver they were found in 6' 6 per cent. of the corpuscles, in a case of chronic malarial anaemia in 11. 5 per cent., while in ankylostomiasis, kalaazar, and rats with trypanosomes and spirochætæ they were detected very frequently. We inferred that an excessive percentage of corpuscles with the granulation was indicative of the discharge of the red corpuscles into the blood stream at an earlier stage in their development than usual, due probably to processes of blood destruction and regeneration which, so far as we know, cannot be estimated by other methods. We now write to call the attention of clinicians more pointedly to the phenomenon in the hope that a study of it in many diseases will prove useful for diagnosis and treatment. Probably the simplest method for demonstrating the granulation is the glass-rod method of liquid staining described by one of us hereafter. A polychrome saturated solution of methylene blue in 0.5 per cent. salt solution should be used. In about a quarter or half of an hour many of the red corpuscles are found to contain minute blue points, often lying in strings, either few in number or so numerous as to fill a large part of the corpuscle. The granules look like small particles of stain adhering to the surface of the corpuscle; but, of course, are not really of this nature. True nucleated red corpuscles can be easily distinguished by the fact that the nuclear membrane is still intact. To estimate the percentage of granular red corpuscles as quickly as possible the following procedure is the best. The whole area of the field should not be examined, but the corpuscles should be passed rapidly in review one by one across the centre of the field and be counted as they pass, and as each granular corpuscle comes up an assistant should score a mark on a piece of paper. In this way nearly a hundred corpuscles may be scrutinised by the minute. In order to avoid serious error of " random sampling " at least a thousand corpuscles should be examined; but if the percentage of granular corpuscles is over 5 of this first thousand corpuscles we should examine another thousand, or if it is over 10, 15, &c., we should examine another two or three thousand, &c. Many of the granular corpuscles, when stained with polychrome methylene blue, will often be found to contain after half an hour, in addition to the blue granules, one or more large deep crimson dots. These are the centrosomes of the original cell, as shown in our paper already referred to. It is possible that an estimate of the percentage of granular corpuscles which contain them will also prove to be of assistance in diagnosis. Nissle has independently just called attention to what appear to be the same bodies but does not give drawings. 3 Some Simple Methods for Staining Liquid Blood, by Professor RoxALD Ross.-The staining of dried films is now being abandoned more and more for cytological work, and it may therefore be worth while to describe briefly some methods 1 The two short articles which follow are records of work done at the Johnston Laboratories, University of Liverpool. 2 Ross, Moore, and Walker : Transactions of the Pathological Society of London, vol. lviii., part 1. 1907. 3 Nissle: Archiv für Hygiene, Munchen, Band lxi. for making sufficiently thin stained films of liquid blood. Several such are given in text-books of hæmatology. One of the oldest, which was suggested by Soulie in 1890,* but was probably known long previously and has certainly been often re-discovered since, consists in spreading and drying a film of alcoholic solution of a stain on a glass slide and then placing over it the cover-glass charged with a droplet of blood. The elements soon take up the colour and beautiful preparations can be made, though there is often much granular matter and the blood does not always spread well. 1. Glass-rod method.-The plan of mixing the droplet of blood with aqueous solutions of stain in various ways has, of course, been largely used. The difficulty lies in getting a sufficiently thin film, because as a rule there is too much fluid in the mixture to allow of a single layer of corpuscles being obtained. After trying many methods I find the following one to be the simplest and best. A large drop of blood is taken up on a glass slide, and a drop of stain, not larger than the drop of blood, is quickly placed close beside it with the end of a glass rod. Then, with the other end of the rod the two drops are thoroughly mixed together, and small quantities of the mixture (say, of the size of a pin's head) are transplanted on to several other slides (just previously wiped clean from dust), where each is covered with a coverslip gently let down upon it. The smaller the droplet of mixture transplanted the thinner the resulting film, and the advantage of the use of the glass rod in this manner is that we can transplant droplets as small as we please and consequently obtain films of any tenuity we may wish for. Specimens for a considerable class may thus be made from a single drop of blood. Aqueous solutions of many stains may be employed and will not generally dissolve the red corpuscles if the amount of solution used is not in excess of the amount of blood. One of the most useful stains is an old polychrome filtered saturated aqueous solution of methylene blue in 0' 5 per cent. salt solution. Large areas, with separate corpuscles in single layer, yet not too much crushed, are obtained, just as in the best dried films. The leucocytes and blood plates are stained almost at once, although the background is almost colourless. A little later the red corpuscles take a blue tinge, and the chromolinin granules and centrosomes of a certain percentage of them 5 (which are not easily disclosed in dry stained films) begin to show up-the granules coloured blue and the centrosomes deep ruby red. The centrosomes of leucocytes are also coloured red ; and it is important to note that the blood plates show similar minute red points, which, if they also are centrosomes, as is possible, will establish the long-contested cellular nature of these bodies. Trypanosomes can be well stained by several reagents. I am beginning to use this method generally in place of the ordinary unstained wet films. 2. Agar method. -Ordinary nutrient agar is melted and mixed with filtered saturated solutions of various stains (e.g., polychrome methylene blue) and poured on sloped glass slides, so as to obtain very thin films of the stained agar on the glass. The agar sets on the glass almost at once but does not dry until some time later. While its surface is still moist a coverslip charged with a droplet of blood is dropped upon it. The blood spreads out beautifully, the red corpuscles being generally disposed in a single layer of perfect discs. In a few minutes the elements take up the stain by adsorption from the-stained agar, centrosomes and chromolinin granulation becoming apparent later. The picture is similar to that of Method I. but perhaps a little inferior, as the staining is not so vivid and the background is not so clear. Deetjen, so far as he can be understood, seems to have used this method but only partially in his study of blood plates 6 ; but on the whole I do not think it is as good, even for this purpose, as Method I. The agar should be as deeply stained as possible, so as to stain the cells quickly ; but the film of it on the glass should be as thin as possible, so as to allow sufficient light through it.