TRYPANOSOMES IN TSETSE-FLIES AND OTHER DIPTERA. 241 
Nov. 8th (120 hours after infection).—Five flies (four 
males, one female) were dissected and examined for trypano- 
somes. In each case the examination was extended to the 
red and black blood, the proventriculus and proctodzum, and 
either -the testes and seminal vesicles, or the ovaries and the 
larva (present in one case). No trypanosomes were found. 
Nov. 10th (168 hours after infection).—Three flies (all males) 
were dissected and all organs carefully examined. In one of 
them nothing was found; the other two were found to be 
infected with Trypanosoma grayi. 
In the first fly the intestine contained a small amount of 
black blood, in which were corpuscles of normal appearance. 
No trypanosomes were found in the proventriculus, black 
blood, testes, or seminal vesicles, but the proctodeeum con- 
tained slender, very active, and rapidly motile trypanosomes. 
One smear was made which showed fairly numerous trypano- 
somes of moderately slender type (figs. 132-135). Round 
forms (fig. 136) also occur, and others transitional (fig. 137), 
between the round forms and the prevailing slender type. No 
dividing forms were seen, nor any encysting forms (for further 
description see p. 195). 
In the second fly also the intestine contained a fair amount 
of black blood and no red. Trypanosomes were found swarm- 
ing in the proctodseum and black blood ; none were found in 
the proventriculus, the testes, or the seminal vesicles. Smears 
were made of the proctodeum and the black blood. ‘he 
smears of the proctodzeum showed an immense number of 
slender forms with very long flagella, n large, transverse, 
always in front of N (figs. 144-146), also a few plumper, 
shorter forms, with the flagellum short and thick, as if being 
retracted, as in encysting forms, but without any cyst-wall 
(figs. 148-150) ; and, finally, a very few cysts, which, how- 
ever, always showed the cyst-wall damaged and spread out, 
probably owing to the thinness of the smear; no dividing 
forms seen, with one doubtful exception (fig. 147). In the 
smears of the black blood trypanosomes were also found very 
abundantly and of types startlingly different from those in 
