RYPANOSOMES IN TSETSE-FLIES AND OTHER DIPTERA. 177 
the posterior end, but may be a short distance from it when 
the posterior end is prolonged into a point. The kineto- 
nucleus is usually a minute round body, but may be rod- 
shaped, a form possibly connected with impending division, 
though this seems to me doubtful. I observed that in slender 
forms the’ kinetonucleus, if rod-shaped, was placed trans- 
versely (figs. 12, 80), but in stumpy forms the rod-shaped 
kinetonucleus was applied to the surface of the body and had 
a more longitudinal direction (figs. 34,35). In good prepara- 
tions it can always be seen clearly that the flagellum does not 
arise directly from the kinetonucleus, but from a minute 
granule, which, as stated above, I regard as the true blepharo- 
plast. In some cases the blepharoplast may be very close to 
the kinetonucleus, or may be over or under it in the prepara- 
tion, giving the impression that the flagellum arises directly 
from the kinetonucleus. The marginal flagellum stands well 
off from the body, forming an undulating membrane of some 
depth when seen in profile. The distinction between body 
and undulating membrane is sharp in osmic preparations, but 
less so in films fixed by drying, owing, I believe, to the 
deformation and flattening out of the body produced by the 
latter method. The-flagellum takes, in fixed preparations, 
a variable number of turns, corresponding to pleats in the 
undulating membrane, which depend probably on the move- 
ments of the animal at the time when it was fixed; but as a 
rule the membrane is least pleated in the extreme forms, both 
slender and stumpy (compare figs. 5 and 13), most so in the 
intermediate form. The anterior end of the body is pro- 
longed into a slender filament, running parallel to the 
flagellum, sometimes nearly to the end of it. 
Most previous observers have described and figured 
T. gambiense as being vacuolated (see especially Bruce 
and Nabarro [5] and Castellani [13]). It has been regarded 
as almost a normal feature of the species to have a vacuole 
near the kinetonucleus.! In my experience these vacuolated 
1 << Wiir besonders charakteristisch wird von einiger Forschern eine Vakuole 
gehalten, die .. . . nicht immer in gleicher Deutlichkeit hervortritt,” 
Lihe (26), p. 115. 
