(e) Wash, dry, and mount. preparations are examined dry. Ehrlich-Biondi In these preparations the red corpuscles are stained red, the malarial organisms and the nuclei of the leukocytes blue. (2) Whitney's Method. (a) Spread the blood as usual; dry thoroughly in the air or by gentle heat. (b) Treat for twenty seconds with the following modification of Zenker's fluid: Potassium bichromate, Sodium sulphate, Water, 2 gm.; I gm.; IOO C.C. Saturate while warm with corrosive sublimate. Add 5 per cent. of strong nitric acid at time of using. (c) Wash in water, and dry with filter-paper. (d) Cover with Ehrlich's triacid stain' for three minutes. (e) Wash, dry, and mount. Unna's polychrome methylene-blue and the Chenzinsky-Plein eosin and methylene-blue3 solution work well after this fixation, but not Löffler's methylene-blue. 1 See Appendix, page 172. APPENDIX. I. BACTERIAL MEASUREMENTS BY PHOTOG RAPHY. Wilson and Randolph' recommend the following procedure for accurately measuring bacteria : (a) Prepare a drawing about four times the size of the desired negative by ruling with ink two sets of equidistant lines at right angles to each other, making every tenth line somewhat heavier than the others. (b) Reduce this drawing by photography to such a size that the rulings are exactly 1 millimeter apart. (c) Adjust the photographic apparatus so that an amplification of 1000 diameters is secured. Obtain this by measuring the image of a stage micrometer on the ground-glass screen. (d) With this adjustment make a photomicrograph of the bacteria to be measured. (e) Superimpose the print of the photomicrograph of the bacteria on the print of the scale, or 1Journal of Applied Microscopy, vol. ii, No. 11, Nov., 1899. II. MOULDS AND YEASTS. Moulds and yeasts frequently contaminate plate and tube cultures, and inasmuch as these growths are occasionally the cause of pathologic conditions, FIG. 94.-Saccharomyces cerevisiæ. it is advisable that the bacteriologist be acquainted with certain typical forms. FIG. 95.-Mucor racemosus: a, spore-bearing head; b, spores; c, branch; d, resting spores (after Jelliffe). |