MICROSCOPY. 459 MICROSCOPY. ber of lyniphocytes, is frequent in the later weeks of typhoid, in ameniia, in intestinal diseases of children, and in lymphatic leucoeytha-niia. Per- sistent increase in the number of white l)lood cells independent of other lesions is characteristic of leucocythaemia. This increase may be very great, and is usually irregular, i.e. the proportionate numerical relation of the different kinds of white blond cells is changed. In lymphatic leucocy- tlia>inia the greatest increase is in the lymph- ocytes. In myelogenous leucocythsemia the in- crease in leucocytes is often enormous, sometimes more than a million per cubic millimeter. Ab- normal forms of leucocytes also appear. In patients suffering from malaria the Plas- modium malarife may be found. The forais which the organism assumes are known as tertian, quartan, and sestivo-autumnal. They occur with- in the red blood cells, rarely in the plasma. The recognition of the malarial parasite requires ex- tremely careful technique and experience. For more detailed description of the parasite and of the methods used in the detection of the same the reader is referred to Delaficld and Pi-udden's Bandbook of Pathological Analomy and Histol- ogy, ed. 6, with references on page 259. Free pigment Is sometimes found in the blood. This condition is known as melanipmia. V'arious foreign bodies such as fat, air, bac- teria, animal parasites (distoma haematobium, filaria sanguinis hominis, and the eggs of the trichina and echinococcus), endothelial cells, pus cells, tumor cells, etc., are sometimes found in the blood. Examination of the blood in typhoid for the so- called Widal reaction should be mentioned. The blood or serum to be examined is mixed with ten times its amount of a twenty-four-hour-old broth culture of the typhoid bacillus and examined under the oil immersion lens. A positive reaction consists in the rendering motionless of the bacilli and their collection into groups. If a reaction with the one to ten dihition occurs, a one to twenty should be tried. Positive reaction with the one to twenty dilution makes the diagnosis of typhoid extremely probable. A negative result is of less value. Stains may be examined to determine the presence or absence of blood, as follows. A drop of normal saline solution to which a few scrap- ings from the stain have been added is evaporated on a glass slide. This is then covered and a drop of glacial acetic acid allowed to run inidcr the cover. The preparation is next heated until it lnilil)lps. More acid is added and the slide heated until a brownish color appears. The specimen is then slowly dried and mounted in glycerin. If any blood was present it is shown by the presence of small rhombic crystals which result from the conversion of lurmoglobin into ha>min. Ficces may be examined by mixing a small amount with a drop of normal saline solution on a glass slide and covering with a cover glass. Detritus from incomplete digestion of food forms a large part of normal fa>ces. Thus it is com- mon to find in a specimen of fa-ces vegetable cells of various kinds, starch granules, muscle fibres from meat, fat globules, coagulated al- bumins, etc. In addition to these there are usually found mucus and epithelial cells, and not infrequently crystals of calcium oxalate, calcium phosphate, calcium sulphate, the fatty acids, triple phosphates, cholesterin, etc. Vol. mil— 30. Epithelial cells in large numbers are frequently associated with intestinal catarrh, especially in children. Kcd blood cells may be found in conditions as- sociated with hemorrhage. Pus cells are frequent in catarrhal inflamma- tions of the bowels. They are more abundant when the inflammation is suppurative in char- BACTERIA X 500. acter. In typhoid fever and other ulcerative con- ditions, bits of an ulcer which has sloughed, or groups of epithelium with pus cells attached may be found in the faeces. A large variety of bacteria are present in normal faeces. Some of these gain entrance with the food; others are normal habitats of the gastro-intestinal canal. Among these may be mentioned the Bacillus coli communis, Proteus vulgaris, Leptothrix, and the Bacillus lactis acrogenes. Under certain as yet little imder- stood conditions, it appears that some of these micro-organisms may assume pathological sig- nificance. The typhoid bacillus occurs in the stools of persons suffering from typhoid fever. As its appearance under the microscope is identical with that of the Bacillus coli communis, the two must be dift'erentiated by biological methods. Tubercle bacilli may be found in the fteces. (For method of staining, see Tuberculosis.) Occurring with pulmonary lesions and without intestinal symptoms, their source is visually in swallowed sputum. If, however, symptoms of enteritis are associated Avith tubercle bacilli in the stools, there is certainly a strong probability that the enteritis is tubercular. The 'Comma' bacillus is present in the stools of persons suffering from Asiatic cholera. The AniQjba coli is found in the faeces in amoebic colitis. It is best to examine stools for amceba as soon as possible after their passage and in the warm stage, as their motility is a valuable aid in its detection. Sputum is examined microscopically to deter- mine the character of the secretion of the respira- tory tract. It may be examined by smearing on a cover glass or slide, fixing and staining with dilute aqueous solution of methylene blue. If there are little lumps of cheesy matter scattered through the R]nitum, it is well to select one of these from which to make the smear, especially
