Drs Fantham and Porter, Some Insect Flagellates, etc. 39 
Some Insect Flagellates introduced into Vertebrates. By H. B. 
_ Fanruay, D.Sc., B.A., Christ’s College, Cambridge, and Liverpool 
School of Tropical Medicine, and ANNIE PorTER, D.Sc., Beit 
Memorial Research Fellow, Quick Laboratory, Cambridge. 
(Plate I.) 
[Received 2 November 1914. ead 23 November 1914.] 
Contents. 
PAGE 
if Introduction . ; ‘ ; F ‘ : : : ; 39 
Il. The Life-cycle of Herpetomonas jaculum in Nepa cinerea . 40 
Ill. Experimental work : : : : : : : ; 4] 
IV. The Morphology of Herpetomonas jaculum in the Mouse . 45 
V. The forms of Herpetomonas jaculum most infective to Mice . 46 
VI. Comparison of the forms of H. jaculum found in the 
Vertebrate with those present in the natural Insect 
Host : : : : ; : : 3 : : 47 
Vil. Comparison of the Induced Herpetomoniasis of the Mouse 
with Leishmaniasis : : : : : ‘ ; 48 
VIII. General Conclusions . , : : ; : ; : 48 
References. : : Z : : : : . : 49 
Explanation of Plate I. : : : : ‘ : : 50 
I. Introduction. 
For some years past, much attention has been devoted to the 
protozoal parasites that produce disease in vertebrates and to 
the means whereby the minute organisms reach their hosts. In 
the latter connection, the rédle of insects in the spread of disease 
has been investigated and much necessary work has been done in 
elucidating the life-histories, more particularly of the parasitic 
Flagellates peculiar to the insects alone, and having no connection 
with vertebrate maladies. It has been generally considered that 
such natural flagellates of insects are harmless to their host, and 
in several cases, notably in the case of Herpetomonas pediculr 
(Fantham), parasitic in the human louse, and Crithidia pulicis 
(Porter), occurring in the human flea, they have been shown to 
have no deleterious effect when introduced into the human system. 
However, all flagellates peculiar to insects are not innocuous, 
should they reach the vertebrate on which their host feeds. By 
a series of interesting experiments Laveran and Franchini have 
recently shown that an experimental leishmaniasis (herpeto- 
moniasis) can be induced in mice and rats by inoculating or feed- 
ing them with Herpetomonas patton: (Swingle), parasitic in the 
gut of rat-fleas, and in dogs by inoculating them with H. ctenocephali 
(Fantham), parasitic in dog-fleas, among others. The introduction 
of the flagellate into the vertebrate produced disease, and death 
