46 Drs Fantham and Porter, Some Insect Flagellates ! 
Some rounded, leishmaniform parasites have also been foun 
within leucocytes (Fig. 20), though these were never numerous, 
The non-flagellate forms measure 4 to 6m by 2p to 3p. 
The body of the mature flagellate varies from 3p to 32 p, its 
breadth being 1°6 w to 2°5 u, while the free flagellum may reach 
35 4 in length. The dimensions thus agree with those of H. 
jaculum in the insect. 
We did not observe many small rounded elements, often uni- 
nucleate, and about 1 to 2 in diameter, occurring in red blood 
corpuscles of infected vertebrates, as described by Laveran and | 
Franchini. Before discussing such endoglobular elements further i 
we wish to conduct more experiments. Such elements do not | 
occur in natural leishmaniases. 
| 
V. The forms of HERPETOMONAS JACULUM most | 
infective to Mice. | 
When the parasites are first seen in the circulating blood, they | 
are usually in the form of small, leishmaniform bodies, and are | 
usually free in the blood plasma. It seems very probable that 
the flagellate forms introduced into the mice gradually absorb _ 
their flagella and thus become non-flagellate forms which appear 
in the blood in exactly the same way as Fantham (1911) described | 
for Trypanosoma gambiense and T. rhodesiense when inoculated | 
into new hosts. When such rounded forms reached the internal 
organs, they appeared to undergo further development, and the 
parasites were always more numerous in the internal organs than 
in the circulating peripheral blood. In connection with the 
number of herpetomonads present in the hosts and the degree of | 
illness produced in them, several features of interest have come to- 
light as a result of our experiments. 
The appearance of the parasites in the peripheral blood was — 
almost as early in the case of mice fed with the intestines of | 
Nepa cinerea infected with Herpetomonas jaculum, as in the case 
of those inoculated intraperitoneally. (See Expts. 2 and 3.) 
The largest number of non-flagellate, rounded forms of H.— 
jaculum occurred in the mice fed with the intestines of Nepa 
cinerea. . 
The largest number of flagellate H. jaculwm also was present 
in the mice fed on the intestines of Nepa cinerea. 
Very few flagellate and but few non-flagellate forms of H. 
jaculum occurred in the case of the mice fed on the fore-guts 
of the infected Nepa, while mice inoculated intraperitoneally 
showed an infection of flagellates considerably smaller than im 
the case of the mice fed on intestine, though slightly greater than 
those fed on the fore-guts of Nepa. 
