Page:Tropical Diseases.djvu/75

II] cent.) and prolonged staining. The stain is dropped on the slip and covered with a watch-glass; after six to eight hours it is washed off with water, the slide dried, and a cover-glass applied with xylol balsam. On examining with a one-twelfth immersion lens slides prepared with methylene blue, the nuclei of the white corpuscles are seen to be very deeply stained, the protoplasm of the white corpuscles is very lightly stained, whilst the parasites are stained an intermediate tint, and show up sharply enough in the faintly tinted red blood-corpuscles (Figs. 2, 16, 20). Contrast staining with eosin is uncertain in its results in methylene-blue preparations; even in practised hands good preparations are the exception. For ordinary purposes I do not recommend it; it is superfluous, troublesome, and unreliable.

On examining successful slides prepared by any of the Romanowsky methods, the red blood-cells will be found to be stained pale pink or greenish; the polynuclear leucocytes will show nuclear network ruby-red, the margins of the nuclei being sharply defined, whilst the protoplasm is unstained, except such fine eosinophil granules as it may contain, which are red; the mononuclears and lymphocytes have sharply defined ruby-red nuclei and faint blue protoplasm; the coarse-grained eosinophiles have a less deeply stained ruby-red nucleus and pale pink granules; the basophiles have dark purple-black granules and ruby-red nucleus; nucleated red cells have almost a black and sharply defined nucleus; the blood-plates are deep ruby-red with spiky margins and sometimes a pale blue peripheral zone. The body of the malarial parasite is stained blue and the chromatin of the nuclei ruby-red; and, in deeply stained preparations of the tertian parasite, the hæmoglobin of the including red blood-corpuscles will be dotted over with certain fine or coarse red granules known as Schüffner's dots.