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! f introduced into Vertebrates 43 
liver and spleen contained a few flagellate and non-flagellate forms. 
‘They were also present, though very rare, in the bone-marrow. 
No parasites were found in smears of other organs or in the 
peritoneal exudate. The control mouse, inoculated intraperi- 
toneally with an equal quantity of normal salt solution, showed 
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no parasites at all when killed. 
Experiment 4 (H.B.F.). Young, wild mouse, "7, weight 5 
grams, was fed once with teased oesophagi and stomachs of three 
heavily infected Nepa cinerea. The feeding material contained 
pre-flagellate and young flagellate forms of H. jaculum. Ten 
hours after feeding, a very few non-flagellate forms were found in 
the blood. At 24 hours, they were still very few and the mouse 
was less active. Thirty-six hours after feeding, a rounded, leish- 
maniform non-flagellate was seen in a leucocyte. After this the 
mouse became steadily weaker and it was killed 60 hours after the 
infective feed. The liver was enlarged and also the spleen. The 
latter weighed 05 gram. A few rounded, non-flagellate and 
flagellate forms occurred in the liver and spleen, they were very 
are in the bone-marrow. No other organs were found to be 
infected. The control mouse, fed on milk exclusively, seemed 
quite healthy when it was killed 24 hours after the death of the 
experimental animal, and no herpetomonads in any stage have 
been found in its organs. 
 Laperiment 5 (H.B.F.). A young, wild mouse, ?, weight 6°5 
grams, was fed once with the teased intestines of three Nepa 
cinerea, heavily infected with H. jaculum. In this case post- 
flagellate forms predominated, and many of the flagellates present 
were dividing. Six hours after the feed, a single, free, leishmani- 
form element was found in the blood; at 24 hours a few similar 
forms were found, and the same condition prevailed at 48 hours. 
At 60 hours a flagellate form was seen in the blood. The mouse 
also appeared to be ill, its coat staring and little food being taken. 
It was killed 84 hours after the infective feed, when it weighed 
6 grams. The liver and spleen were enlarged, the latter weighing 
07 gram. The kidneys were more friable than usual. Flagel- 
lates were relatively numerous in the liver, somewhat fewer in the 
bone-marrow and spleen. A few dividing forms occurred. The 
leishmaniform stages were less common on the whole than the 
flagellate forms. The control mouse, fed on milk only, was killed 
by accident the day after the death of the experimental animal. 
Its organs contained no trace of herpetomonads or other parasites. 
) Experiment 6 (H.B.F.). A young, wild mouse, g/, weight 
85 grams, was inoculated intraperitoneally with the guts of two 
infected Nepa teased in normal saline, a control mouse being 
“inoculated with a similar quantity of normal saline alone. Hxami- 
nation of the blood six hours after inoculation showed one 
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