ESSENTIALS OF BACTERIOLOGY 



dissolved in 100 c.c. of pure methyl-alcohol. The smears are 

 dropped into this stain for one to three minutes, without pre- 

 vious fixation, and at once rinsed in distilled water. The 

 malarial parasites are stained blue, the cell-bodies a reddish 

 brown. 



(3) Wright's Chromatin Stain. This is the best of the 

 chromatin stains. For its preparation, which is quite com- 

 plicated, see Wright, Journal of Medical Research, vol. vii, 1902. 

 It is used as follows: 



1. The stain is poured over the film and allowed to remain 

 for one minute to secure fixation. 



2. Add distilled water drop by drop until a metallic scum is 

 formed on the surface. The staining now takes place and 

 requires two to three minutes. Wash in distilled water until a 

 pinkish tint appears in the thin portions of the smear. The 

 body of the malarial parasite is stained blue, and its chromatin 

 a lilac to red color. The red cells are orange pink. 



If possible, examinations for malarial organisms should 

 always be made before quinin is administered. 



Trypanosomata. Trypanosomes are flagellate protozoa 

 found in the blood of various animals, and causing a number of 

 diseases, such as surra, dourine, and nagana, affecting horses 

 and cattle, especially in tropical countries, and causing the 

 sleeping sickness of Africa, which is very fatal for human beings. 



Morphology, A fusiform mass, containing at one end a 

 flagellum. 



In the living state these protozoa are very motile. In the 

 stained specimen chromatin granules are found and two or 

 more nuclei. From the smaller nucleus arises the undulatory 

 membrane, which passes into the flagellum and assists in the 

 wave-like motion. 



In the body fluids division occurs, first of the nucleus, and 

 then of the protoplasm. 



Cultivation. Novy and MacNeal have succeeded in culti- 

 vating these protozoa on blood-agar, and multiplication goes 

 on rapidly, so that rosets are formed with the flagella arranged 

 around a common center. (See Figs. 112, 113, 114.) 



