TRYPANOSOMES IN TSETSE-FLIES AND OTHER DIPTERA. 189 
called it, of T. grayi, the structure of the body is in general 
very uniform, though showing great variations in some 
points. As regards the cytoplasm, I find remarkable differ- 
ences, which are evidently due to differences in the action of 
the stain used (Giemsa’s mixture) ; two types of staining are 
produced which are well exemplified in the series of dividing 
forms figured by me (figs. 204-216), all of which are drawn 
from two preparations made from smears of the same blood, 
and stained in Giemsa’s solution side by side in the same dish. 
In one preparation the cytoplasm is bluish in colour and 
shows coarse granulations deeply stained, while the flagella 
are very faintly stained, appearing sharp and delicate, often 
difficult to make out clearly (figs. 204, 207, 212, 218, 215, 
216). In the other preparation the cytoplasm is reddish in 
tint and the granulations are scarcely seen, or not at all, while 
the flagella are deeply stained and appear thick and very 
distinct (figs. 205, 206, 208-211, 214). The differences in 
- the staining are probably due to differences in the use of 
the Tannin solution, used to differentiate the stain (see 
pal?) 
The nucleus (NV) of I’. grayi presents itself as a clump of 
granules, sometimes compact, oval or round, and in the latter 
case. sometimes showing a distinct rosette-like structure (fig. 
182, and P.R.S., 8B 78, Pl. XIII, figs. 35, 39) ; more often the 
nucleus is quite irregular in shape and loose in texture, and 
in one fly (Nov. 10th, [2], p. 241) the nucleus shows streaks of 
granules apparently trailing irregularly out from it, in nearly 
all the large forms (figs. 138-140). This suggests that the 
coarse granulations of the cytoplasm represent chromidia 
derived from the nucleus; but they stain slightly differently 
with Giemsa’s stain, the granules of the nucleus having a 
redder tint, while the chromidial granules are more ae 
like the kinetonucleus in tint. 
_ The kinetonucleus () is large and rod-shaped, its length 
being about twice its breadth ; it is superficial in position, and 
often appears to bulge from the surface of the body. In 
very thin smears it is often torn out of the body. It is very 
