TRYPANOSOMES IN TSETSE-FLIES AND OTHER DIPTERA. 229 
were dissected and smears made of the blood. They showed 
trypanosomes of elongated, moderately stout form, and others 
of slender type. Dividing forms were also seen (P. R. 8., 
© (Sy dele pO hs Niven, 1E))R 
A remarkable feature of this batch is the excess of slender 
forms over stout. 
Batch of Sept. 8th, 1905.—A batch of flies, caught on 
the island of Kimmi, were fed on Monkey 420. Four 
flies were dissected after two hours, three after six hours, 
and three after twelve hours. 
The smears made from the flies dissected after two hours 
showed slender, stout, and intermediate forms, with many 
division stages. 
In the smears made from flies six hours after feeding, the 
differentiation of stout and slender forms was more marked. 
One fly contained Trypanosoma grayi as well as T. 
gvambiense; unfortunately the preparations were a failure. 
At twelve hours after feeding the differentiation of the 
stout and slender forms appeared to be complete. 
Sept. 9th (twenty-four hours after infection).—Three flies 
were dissected and smears made from them. A fourth fly 
was dissected and the blood examined fresh. In the latter 
no trypanosomes were seen in the red blood; in the black 
blood they were found singly and in groups of two or three 
or even four. The single ones moved rapidly, with flagellum 
forwards. In the groups they were attached by the posterior 
ends with the flagella free ; individuals thus attached were 
sometimes unequal insize. A group of three was observed in 
which four flagella could be distinctly seen, indicating division 
of one of them. A group of four was noted in which one was 
much smaller than the others, and one larger; this group 
separated into two couples; in each couple the trypanosomes 
were attached téte béche, the two nv opposite and close 
together (fig. 110). The smears showed trypanosomes 
differentiated into the normal slender, clear, and stout, 
granular forms (P. R. S., B 78, Pl. XII, figs. 3-5 and 7-9). 
Dividing stages of both forms were common. 
