TRYPANOSOMES IN TSETSE-FLIES AND OTHER DIPTERA. 235 
The third fly (female, forty-seven hours after infection) was 
gorged with blood. ‘The trypanosomes were not very 
numerous ; some were more slender, others stouter in form; 
in the red blood a slender one and a stout one were seen 
hanging on together. 
Smears of the red blood showed stout forms, not very 
numerous, one of which was dividing (fig. 69). Smears of the 
black blood showed trypanosomes fairly numerous, varying 
from a moderately slender to a very stout type (figs. 70-72). 
In one smear were counted 17 slender, 25 stout, 21 inter- 
mediate, and 2 dividing forms. 
The fourth fly (male, forty-eight hours after infection) was of 
emaciated appearance ; the stomach was full of bacteria and 
contained no red blood; the intestine contained black blood 
in which were a few motile trypanosomes. ‘lwo smears were 
made, in each of which a single trypanosome of stout form 
was found. 
The fifth fly (male, fifty hours after infection) had a small 
amount of red blood, in which no trypanosomes were seen, 
and a considerable amount of black blood, in which a few 
active trypanosomes were seen. In the smears, however, no 
trypanosomes could be found. 
Oct. 18th.—Three flies dissected and examined. The first 
fly (male, sixty-nine hours after infection, not re-fed) showed 
a small amount of blood in the intestine, black posteriorly, 
reddish anteriorly. A few motile trypanosomes were seen ; 
none in the proventriculus. In a smear a fair number of 
trypanosomes were seen, slender or moderately stout in type, 
some of them very granular; unfortunately the stain was 
very faint. 
- The second fly (male, seventy hours after infection, not 
re-fed) showed a similar condition to the last. A fair number 
of active trypanosomes were seen in the intestine, some of 
them long and moderately slender, others broader. Three 
trypanosomes, originally quite separate, were seen to come 
together and adhere by their posterior ends. No trypano- 
somes were found in the proventriculus, proctodeum, or 
