4

lights, on entering a house are frequently crushed by the occupants lying on
them, and the resulting blisters soon become chronic sores with indurated mar-
gins and closely simulate the true Cambay Boil.

       As far as I am aware, no observer has as yet carried out exact feeding
experiments with bred house flies in the endemic area, with a view to proving
or disproving the fly transmission hypothesis. In my studies on the herpeto-
monads of the house flies of Madras I had already mastered the best methods for
breeding these insects and keeping them in captivity. During June, July and
August in Cambay, Musca nebulo Fabr. and Musca sp. were extremely abun-
dant, and I do not recollect having seen these insects in such large numbers
and constituting such a pest, in any part of India which I have visited. While
driving from the dâk bungalow to the Hospital where I conducted my experi-
ments, they followed me in large numbers, and in the Hospital itself they were
present in swarms; so much so, that it was difficult to carry on one's work.

EXPERIMENT I.

CAN THE HOUSE FLY CARRY THE PARASITES ON ITS LEGS (PULVILLI) OR ITS
PROBOSCIS, FROM A SORE DISCHARGING PARASITES, AND DEPOSIT
THEM ON A SCRATCH OR ABRASION ON THE SKIN OF

A SUSCEPTIBLE PERSON ?

       This experiment was carried out on my own person; several scratches and
abrasions were made on the dorsum of my left hand, and flies were caught
which had already crawled over and sucked up the whitish discharge from the
sore mentioned above, and which was teeming with apparently living parasites.
They were then allowed to crawl over and suck up the serum from the scratch-
es on my hand. This experiment was carried out daily for about a month, and
it was impossible to prevent the experiment under consideration being also
carried out naturally, not only on my left hand, but on the right, and more
particularly on my face; small cuts such as are commonly caused in shaving
were constantly being contaminated by flies which had previously been on the
sore. In spite of all these attempts, however, I never developed a single lesion
on any of the experimental spots, and now more than a year has elapsed since
they were carried out. Such a series of experiments, conducted in the endemic
area, and under the most favourable conditions, conclusively prove that the
house fly does not carry the parasite in the way mentioned above. In support
of these results, there are the statements of the people of Cambay, who, al-
though they have very crude ideas of the disease and its origin, have no hesi-
tation in saying that the sore never begins in an open cut, scratch or abrasion,
but always in a sound portion of skin.