366 
LEISHMANIA, HERPETOMONAS, AND CRITHIDIA 
IN FLEAS. 
By Dr CARLO BASILE, D.T.M., R.C.Ph.S. (London), 
Libero docente (University of Rome). 
(With Plates XXI and XXII.) 
INTRODUCTION. 
Most of the observations recorded in this paper would have been published 
in 1915, if my duties as a doctor and as an officer had not called me to 
the Army. 
F olio wing on my experimental researches (1910-1915), on the transmission of 
visceral leishmaniasis by means of fleas ( Ctenocephalus canis and Pulex irritans), 
a very interesting problem arose which still rivets the attention of students of 
this subject. 
In the intestine of various insects and of fleas in particular, certain Proto¬ 
zoa of the herpebomonad and crithidial types have been observed. The morpho¬ 
logical, biological and experimental study of these Protozoa in relation to 
Leishmania is particularly interesting. 
Patton maintained that this parasite is a true Herpetomonas , and called 
“herpetomoniasis” those infections which we now call “leishmaniasis.” 
Minchin and Wenyon, on the other hand, observed that although Leishmania 
in some stages presents morphological characteristics almost identical with 
Herpetomonas it is distinguished by the fact that Herpetomonas is only found 
in insects, in whose intestines the different species undergo their complete 
developmental cycle (flagellate and non-flagellate), while Leishmania com¬ 
pletes its cycle in two hosts, one of which is a vertebrate and the other an 
invertebrate. In the vertebrate host Leishmania produces a disease with 
characteristic symptoms—“ Leishmaniasis A 
BIOLOGY AND MORPHOLOGY OF LEISHMANIA . 
The biological and morphological characteristics of the parasite must be 
studied, (a) in the vertebrate host; (b) in artificial cultures; (c) in the trans¬ 
mitting host. 
(a) Leishmania in the vertebrate host is non-flagellate, it appears either 
ova] (Plate XXI, fig. 1), or round, with a diameter varying from 2 to 4/x; it 
may also be pear-shaped (Plate XXI, fig. 3) when it may attain a length of 
7 p. 
