TRYPANOSOMES IN TSETSE-FLIES AND OTHER DIPTERA, 231 
Monkey 478. The flies were kept in a large cage, with water 
and vegetation, in a situation where direct sunlight fell on 
the cage late in the afternoon. Smears of the monkey’s 
blood made the day before (Oct. 2nd) showed a considerable 
amount of differentiation (figs. 6-10), in contrast with the 
smears made from the monkey the day previously (Oct. Ist). 
Stout, slender, and indifferent types could be distinguished ; 
of the first 99, of the second 97, and of the third 34 were 
counted in one smear. Most of the stouter forms were of the 
typical stumpy form (figs. 9 and 10). Specially noteworthy is 
the length of the free’ flagellum in slender forms, and its 
shortness in the stout forms (compare figs. 6 and 7); by this 
character the indifferent forms could also be subdivided into 
two classes. 
It is interesting that the trypanosomes from the blood of 
the same monkey on two consecutive days should show so 
little differentiation on one day, so much the next day. 
Oct. 4th (twenty-four hours after infection).—Two flies 
were dissected. In the first a few trypanosomes of the stout 
type were seen in the black blood. A smear was made in 
which seven ‘typical stout trypanosomes were counted. In 
the second fly no trypanosomes were found; the stomach 
contained a vast number of bacteria. 
Oct. 5th (forty-eight hours after infection).—One fly was 
dissected, and various organs examined. ‘Trypanosomes were 
found fairly abundantly in the red blood and the black blood. 
The sucking stomach contained a peculiar clot of blood, in 
which, however, no trypanosomes were found. The trypano- 
somes in the fresh condition appeared chiefly of the broad 
type, but one of more serpentine appearance with pointed 
posterior end was noted. 
The smears made were unfortunately very unsatisfactory 
as regards preservation. In the best one, of the red blood, 
a few trypanosomes of moderately stout or moderately slender 
type (figs. 66-68) were found; in some parts of the smear 
they occurred in clumps, three or four together. In the 
smears of the black blood none were found. 
