11 
Many of our rats died. Plain evidences of sickness coupled with 
heavy blood infection were almost sure to give a fatal result. We 
made no pathological study of the internal organs. 
STAINING. 
In the beginning we attempted to stain the parasites with the ordi- 
nary aniline dyes. We used eosin, methylene blue, hemalum, carbo- 
fuchsin, and carbo-thionin, but all were very disappointing. We 
then turned to the Romanowsky double stain of methylene blue and 
and eosin, Goldhorn’s polychrome methylene blue and Jenner’s stain, 
all of which give most beautiful elfects indeed; perhaps the best is 
Romanowsky’s stain. Some modification of this stain is the one which 
many of the investigators have emploj^ed within the last few years for 
trypanosomes. In the hands of the various experimenters this stain 
seems to give somewhat different effects. The two points on which 
they all agree are that the nucleus takes a beautiful rose red and that 
the protoplasm takes a blue color. Rabinowitsch and Kempner state, 
and it is clearly shown in their figures, that in the hind part of the 
adult parasite there is an oval or round spot of a homogeneous struc- 
ture which takes the stain uniformly and intensely red. In the front 
end of the trypanosome is a larger body with a net-like structure 
which stains rose red. In their hands the x^i’otoplasm of the body and 
the free outer border of the undulating membrane and the fiagellum 
stained quite uniformly blue. The web of the membrane remained 
unstained. 
Wasielewski and Senn state that the protoplasm is almost homo- 
geneous, stains a light blue, and has a fine granular structure. In it 
are one to three clear, oval areas, generally in front of the centrosome, 
which can be considered as vacuoles. With the Romanowsky stain 
they succeeded in giving a red tint, not only to the centrosome and 
nucleus, but to the free border of the undulating membrane, to the 
web of the undulating membrane, to the fiagellum, and to the entire 
border of the body of the parasite. They state, however, that the 
tint of the centrosome, flagellum, undulating membrane, and “peri- 
plast ” was a bluish red. 
Laveran and Mesnil picture the centrosome and body of the para- 
site as blue, and the nucleus, flagellum, and undulating membrane as 
red. With Romanowsky’s stain we gave a blue color to the body of the 
trypanosome. The nucleus took a rose red, and the centrosome was 
deep red. The flagellum and border of the undulating membrane 
were red, and the web of the undulating membrane was faintly red. 
WrighVs modification of Romanoiosky^s stain . — Wright (7), in 
speaking of Romanowsky’s stain, which came out in 1891 as a differ- 
ential stain for the chromatin and cytoplasm of the malarial parasite, 
refers to the difficulties and uncertainties attending the preparation 
of the stain until it became finally modified by Leishman (8), whose 
