1 1
evident there were grave sources of error in Schaudinn's experiments. Ross, Novy, MacNeal
and Torrey have recently pointed out that although Schaudinn referred to Leger's observations
on Crithidia fasiculata from Anopheles maculipennis,he makes no mention of the similar parasites
of Culex mosquitoes and as the species Culex pipiens which he was dealing with was presumably
captured at large at Rovignio, it was necessary to first exclude the possibility of it harbouring
these natural flagellates. Schaudinn's work has led to the erroneous belief that these insect
flagellates when occurring in blood-sucking insects represent the further development of some
unknown Hœmofla flagellate.
Ross when carrying out his memorable observations on the evolution of the malarial
parasites of birds in mosquitoes found flagellates in a mosquito (Culex) which had fed on birds
infected. with Halteridium and Proteosoma and on examining another mosquito which had not fed
on the birds he found similar flagellates and also their earlier stages in the alimentary tracts of its
.
larva and pupa. He rightly concluded that they had. no connection with the Hœmocytozoa of birds,
but were true insect parasites and that the infection was probably acquired by the larva. I have
been able to confirm these observations of Ross and in a recent paper I gave a short account of
the life cycle of a species of Herpetomonas which is commonly found in Culex quasi pipiens
and Culex fatigans. The larvæ of these mosquitoes ingest the cysts which are passed out by
the adult mosquitoes, and on passing down to the lower end of the small intestine, they multiply
rapidly either dividing by simple biniary fission or by multiple segmentation ; in the nymphs
further development takes place some of the parasites flagellate while others develop into
rosettes of from twenty to more flagellates. In the adult mosquito the majority of parasites
have already become flagellates and three days later they begin to pass down to the rectum and
on becoming attached in rows by their flagellar ends they shorten and divide at the same time
the flagella are shed. They now become rounded and are often full of large chromatoid gra-
nules which may obscure the nucleus and blepharoplast ; they are surrounded by a well marked
periplast which stains pink with Giemsa's stain. These cysts are eventually passed out in the fæces
of the mosquito probably when it is laying its eggs in water and identical bodies can be found
in the larvæ so that there can be little doubt they are ingested at this stage. These observations
bring out some points of importance. Although these mosquitoes particularly Culex fatigans
suck human blood and that of a number of animals this Herpetomonas has no connection with any
blood parasite, but passes its complete cycle in the mosquito ; its structure and life cycle at once
suggest that of the parasite of Kala-Azar. The similarity between the flagellate stages of the
two parasites is obvious, but the resemblance of the non-flagellate stage of Herpetomonas to the
well-known human parasite is less widely recognised. Still more recently I have succeeded in
finding a new species of Herpetomonas in the alimentary tract of the Lygœid bug
Lygœus
militaries, which is almost identical with the Leishman-Donovan body. The cysts as in the case
of Herpetomonas mentioned above are ingested by the bugs, adults or nymphs, they divide twice
by simple longitudinal division resulting in characteristic groups of four bodies, these latter
flagellate and after remaining an indefinite time in the upper part of the alimentary tract of
t h e b u g p a s s d o w n t o t h e r e c t u m w h e r e t h e y e n c y s t . T h e y s h o r t e n a n d d i v i d e a b o u t t h r e e
times the flagella being shed at an early stage and the resulting bodies are very like the Leish
man-Donovan parasite. They are passed out in the faces of the bug and are again ingested
by other bugs. A similar process of division has been observed in the later stages of the develop-
ment of the parasite of Kala-A zar in Cimex rotundatus which suggests that it passes back to its
non-flagellate stage in the bug probably in its pharynx and is thus reintroduced into man. A full
account of this Herpetomonas will shortly appear in the Archiv fur Protestinkunde.
The following species of Herpetomonas have been found to be common here:—
Herpepetomonas muscœ domesticœ (Burnett) in Musca domestica.
sp. ?
in Lucelia sp.
„ Sarcophagœ (Prowazek)
in Sarcophaga sp.
,,
sp. ?
in Stomoxy's sp.
Herpetomonas lyagœi (Patton)
in Lygaus militaris.
,,
, 8p. ? in Culex fatigans, and Culex quasi pipiens.
,,
sp. ?
in Ctenocephalus fells.
In their adult flagellate stages all these parasites are characterised by the complete absence
of an undulating membrane the single flagellum having a short intracellular portion owing to
the blepharoplast occupying a position almost at the anterior end. As far as it is possible
to say at present at least three of these, Herpetomonas muscœ domesticœ, Herpetomonas sp. P
from Lucelia and Herpetomonas sarcophagœ are closely allied and should be grouped together.
o
f Herpetomonas lygœi is more closely related to the Leishman-Donovan body, while the Herp
tomonas of Culex pipiens occupies an intermediate position. As our knowledge of these flagellates
increases it will undoubtedly be found necessary to further sub-divide the genus into one or more
sub-genera but in the meantime it will be wisest to place them all in the genus
Herpetomonas of Kent.
In addition to these flagellates certain insects are infected with another type for which
Leger has created the genus Crithidia. In a paper which will shortly be published in the
Archiv für Protestinkunde, I have given a complete account of one of these parasites, Crithidia
gerridis, which I found in three water bugs.