460 
THOMPSON YATES LABORATORIES REPORT 
Stained Preparations. Most of the blood films were stained by a slight modifi- 
cation of the method of Romanowsky for chromatin ; this method brings out well 
the structure of the parasite. 
The length of the parasite, in stained preparations, including the flagellum, varied 
from 18 n to 25 fx ; in preparations which were taken on December 16 (first obser- 
vation) the parasites appeared somewhat longer than those taken when they appeared 
in the blood again on December 27 the majority of specimens measured 22 //, the 
width was 2 /x to 2- 8 u- This width, when compared to the other typanosomes is 
distinctly greater in proportion to the length. 
The flagellum stains a light crimson, and can be traced from the anterior end of 
the organism along the outer margin of the undulating membrane, stopping short of 
the refractile spot seen in fresh preparations ; it sets in small curves along the body, 
and there is always present a dip opposite the nucleus. The free part of the flagellum 
is about one third that of the total length, but it is difficult to say where the anterior 
part of the body ends and the flagellum begins ; one can always see a narrow streak 
of protoplasm, staining blue, for some distance beneath the free part of the 
flagellum. 
The posterior end of the organism is roughly conical, in most specimens with 
the point ot the cone cut away on the side remote from the undulating membrane ; 
it is very blunt. 
The undulating membrane is a narrow unstained band, somewhat wrinkled, 
attached along one side of the animal ; in stained preparations, it sometimes takes 
on a taint pink colour. 
The nucleus (the macro-nucleus of Plimmer and Bradford) is situated a little 
anterior to the middle of the body, in some specimens occupying the whole width 
of the animal ; it is oval in shape and stains dark crimson, due to an aggregation of 
chromatin granules. 
Generally about 2 - 5 from the posterior end is a dark purple spot, well marked, 
shewing no definite structure ; this is the centrosome (Laveran and Mesnil) or 
micro-nucleus of Plimmer and Bradford. Anterior to it there is a large clear spot 
(vacuole) which does not stain ; the vacuole in all the specimens is well marked ; the 
flagellum appears to end at the upper edge of the vacuole. Laveran and Mesnil 2 
point out the connexion ot the flagellum with centrosome from observations on 
T. lewisi. 
The protoplasm does not stain evenly, it takes on a basophil reaction, and in it 
are fine blue-stained granules situated chiefly beneath the attachment of the undu- 
lating membrane, and also around the nucleus. Plate VI shews the trypanosomes stained 
by Romanowsky's method. The organisms 'set' in a characteristic manner on a 
1. Plimmer and Bradford state, the size and length of the body of T. Brucei varies very much with the period of the 
disease. S^tart. Journ. of Microscop. Sc., vol.45, pt. 3, p. 452. Feb., 1902. 
2. Sur le Trypanosoma des Rats (T. lewisi Kent). Ann. de I'Institut Pasteur, September 25, 1901, p. 684 
