A guide to the clinical examination of the blood for diagnostic purposes / by Richard C. Cabot.

  • Cabot, Richard C. (Richard Clarke), 1868-1939.
Date:
1901
Catalogue details

Licence: Public Domain Mark

Credit: A guide to the clinical examination of the blood for diagnostic purposes / by Richard C. Cabot. Source: Wellcome Collection.

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    but there is no harm in holding it with the fingers, provided we avoid touching either of its surfaces, i.e., hold it always as in Pig. I.1 Slide and cover must be perfectly clean, else the blood will not spread out in a layer thin enough to avoid the corpuscles overlying each other so that not one of them is clearly seen. Further, as dirt simulates fairly closely some of the pathological ap¬ pearances for which we are on the look¬ out, its presence on the slide leads to loss of time or to mistaken conclusions. Cover- glasses, as they come from the shops, may be coated with a substance not easily to be removed. To get them really clean FIG* 1*“Prop!;r Method of Hoid- nothing is so simple as or more effective than soap and water. After several years’ use of the method of cleaning usually advised (viz., strong mineral acid, followed by alcohol and then by ether), I have become converted to the use of plain soap and water as the best and simplest way of cleaning slides or cover-glasses. Rub soap over every part of the glass, wash it off with water, and polish it thoroughly with a clean handkerchief (most towels are apt to leave a scrap of lint on the glass).2 If slide and cover are perfectly clean, are held as in Fig. 1, and allowed to touch only the summit of the blood drop and not the skin, the blood will spread out properly between them, and no pressure on the cover-glass will be needed to make the layer of cor¬ puscles thin enough. Pressure is undesirable, as it often makes all sorts of artefacts in the preparation and hastens crenation of the red corpuscles. Better results are obtained if slide and cover are warmed just before using, and it is well to have an assistant rub the slide vigorously with a towel just before it is used. This method is, of course, applicable only to specimens to be 11 am not unmindful of Ehrlich’s warning that the moisture of the fingers spoils the specimen; hut in practice I do not find it to he true except as re¬ gards the margin of the film, the good preservation of which is not essential. Only the thinnest cover-glasses in the market should he used. | inch is the hest size. 2 Further experience has convinced me that water alone is generally suffi cient, provided the polishing, which is the chief factor of success, is thorough. Tissue paper is very useful for polishing cover-glasses. After polishing, it is well to pass them through a Bunsen or alcohol flame once or twice.