9 
the nucleus is arranged in a spoke-like fashion (‘ rad- 
kern ’). The nucleus is at one side of the cell and is 
separated from the cytoplasm by a halo. 
The leucocytes may be studied and counted in films 
stained with Romanowsky, but for many purposes it is 
advantageous to use one or more of the following stains. 
For studying the character of the nuclei, haematein is 
the best; for the granules, Ehrlich’s triacid; and for 
mast granules, Jenner. 
1. Ehrlich's Triacid {vide p. 408).—Fix with heat 
(p. 20). Without shaking the bottle pipette off enough 
to cover the blood film. Stain for five minutes. Wash 
in water. The neutrophil granules (e) are reddish 
violet; the eosinophil (a) are coppery red; the red cells, 
orange; the mast granules and basophilia of the red cell 
are not shown. The stain is best made by one’s self. 
2. Eosin and Methylene Blue. —Fix with heat, 
stain with eosin (p. 408) three minutes. Wash (and 
dry). Stain with methylene blue (p. 408) two parts and 
eosin one part, freshly mixed, for half a minute. Wash. 
Dry. 
3. Eosin and haematein. —Fix the film. Stain 
with eosin three minutes. Wash, stain with haematein 
(p. 408) half to one minute. Haematein is especially 
good for studying the differences in the nuclei. 
4. Jenner's Stain is the precipitate resulting 
from the action of a watery solution of eosin on a watery 
solution of pure unripened methylene blue ; dissolved 
in methyl alcohol (Tabloid 0*05 gramme; methyl alcohol 
10 c.c.). 
To stain. —Fixing is unnecessary. Place solution 
on film, covering so as to avoid evaporation. Stain 
two to three minutes. Add about twice as much H 2 0 
to the slide. Mix. Stain five to ten minutes. 
Especially adapted for the mast granules. 
