vii
of those people who 'came to Cambay for short periods were infected during the cold weather.
Bugs were then kept in a tin box surrounded with ice and in one bug dissected shortly after-
- wards the flagellate stage was recovered. The experiments were continued in Cambay and
later in Madras, and it has been definitely settled that the parasite will only flagellate
in the bug below a certain temperature (72° F.-75°F.), but that it dies out in the adult
bug. Further experiments are now in progress with the nymphal stage of the bug to try
and see whether the parasite will complete its development in one or other of the nymphal
instars.
The etiology of Kala-Azar. —Recently I had an opportunity of feeding bugs, Cimex rotun--
datums, Cimex leeularius and Conorhinus rubrofasciatus , on a case of Kala-A-zar in whose peril -
pheral blood there were hundreds of parasites. The bug s used were all bred from the egg and
the first nymphal Minstar fed for the first time on the case ; they were then kept in a cold incu-
- b a t o r a t a b o u t ' 7 2° F . B o t h i nr
o t u n d a t u s
a n d
l e c u l a r i u s
a l l t h e d e v e l o p m e n t a l s t a g e s h a v e b e e n
found and the remaining bugs are now being fed on a case of Kala-Azar in whose blood the
parasite can only b e found in small numbers. These bugs will be dissected at regular intervals
up to the 21 st and 24th day after they are fed on the case mentioned above and in this way it is
hoped to discover the post flagellate stage of the parasite ; it is interesting to note that the
parasite develops in lectularius in precisely the same way as in rotundatus. In Conorhinus rubro-
- f a s c i a t u s
t h e p a r a s i t e d e g e n e r a t e s 1 2 h o u r s a f t e r b e i n g i n g e s t e d , t h i s w a s c l e a r l y d e m o n s t r a t e d
in one of these bugs which had fed twice on the case mentioned above and which had ingested
over 500 parasites. This discovery in the first place shows that this bug cannot possibly be the
natural transmitter of the parasite and secondly it refutes the hypothesis that the parasite of
Kala-Azar only develops in the bug Cimex rotundatus becaus e i t i nges t s a l ar ge quant i t y of
blood. The first nymphal instar of C onorhinus rubrofasciatus ingests an enormous quantity of
blood sufficient to make at least three ordinary blood films ; yet the parasite rapidly dies out in
its stomach. A paper describing the above experiments is now in process of preparation.
Medical Entomology .—A large amount of work on this subject has been accomplished ; the
life histories of all the South Indian biting flies having been worked out as well as those of
ticks fleas and lice. These observations will be published in due course in the Indian Bulletin
of Medical Entomology.
THE STRUCTURE OF THE PROBOSCIS OF PHILAEMATOMYIA
INSIGNIA, AUSTEN.
(Abstract)
By
Captain F. W. Cragg, M .D.,
Philaematomgia insiynis is a small and inconspicuous Dipteron, resembling the common
house fly in its general appearance. It is found in large numbers in the neighbourhood of this
institute, and elsewhere in India, being widely distributed through the Oriental and African
regions. The interest attaching to it lies in the fact that in spite of its innocent appearance and
Musca like habits it is a voracious blood sucker, deriving its food entirely from the blood of
cattle, and perhaps other animals.
The proboscis presents, on a superficial examination, nothing to suggest its true structure.
It possesses the same parts, arranged in the same way, as in Musca domestica or in Calliphora ;
it is completely retractile blunt pointed, and when extended for use hangs downwards at a right
angle to the insects body. The pseudo-tracheal membrane is well developed and apparently
functional, differing from that of Musca only in the smaller number of channels ; the labium-
- e p i p h a r y n x a n d t h e h y p o p h a r y n x a r e a l s o e s s e n t i a l l y s i m i l a r . I n f a c t , s o i n c o n s p i c u o u s a r e t h e
biting parts and so small the degree of modification which has taken place in the proboscis that
it is certain the fly has long passed unnoticed even by those specially interested in biting flies.
The assumption of a blood-sucking habit in this fly is dependent on a high degree of
development of the prestomal teeth, structures which are present throughout the whole Muscle
group In Musca they are attached to a racket shaped loop of strong chitin which surrounds the
entrance to the food canal, and are used by the fly for scraping the surface of its food when this
is necessary in order to obtain the subjacent moisture The great increase in the size of these
teeth has led to secondary changes in the structures which support them and to the increase of
the muscles and surfaces for muscle attachment. The species, in fact, represents an early stage
in the adaptation of the Museid proboscis to a blood-sucking habit, and it has therefore a special
importance in view of the light it throws on the course followed during the evolution of such
highly specialised flies as Glossina.
The teeth are shaped like short and stout thorns, and have coarsely serrated cutting edges ;
there are four on each side, each being attached to the membraneous inner wall of the labellum
by an expanded base, their upper ends are fitted into a concavity formed by the lower ends of
the labellar rods, two stout bars of chitin which represent in this fly the straight proximal part