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     In favour of the fly transmission hypothesis there is the undoubted fact
that people, particularly children, who have a sore discharging parasites, fre-
quently reinfect themselves by scratching the scab or the surroundings of the
sore, and then scratching some other healthy part of the skin. The case I was
studying thus reinfected himself, and it is interesting to note that at the time
he had a great deal of prickly heat, and inoculated three places by scratching
them with infected nails. When the rationale of this auto-infection is carefully
considered, it will be seen that it is exactly similar to vaccination with cow-pox,
for the parasite is deliberately inserted into the skin in the act of scratching.
This method of auto-infection is extremely common, and the Jews in Baghdad
and other parts of the world, have long practised it; recognising the readiness
with which a sore can be produced on any part of the body they select a
place where the resulting scar will cause no disfigurement.

     Several experiments were carried out to try and see whether an already
existing sore, (not the specific lesion) will become infected by placing some of
the whitish discharge containing parasites on the surface of the granulations,
such as a fly may do in the act of crawling over it. The experiments were car-
ried out on three susceptible people who had recently come to Cambay, and in
each case they failed. Lastly, a large number of sores, ulcers, scratches and
abrasions in children, who had up till then not contracted the disease, were
examined for months, but I was never able to find a single parasite in any of
these sores. I consider this observation to be of importance, for it refutes the
numerous loose statements, that during the fly season, when the sores are most
prevalent, such cuts, abrasions, and ulcers are very liable to become infected
with the parasite. These experiments, then, not only prove that the house fly
is not a carrier in the way suggested, but that simple sores and ulcers which are
so common, and always present on Indians, never become infected.

EXPERIMENT II.

DOES THE PARASITE WHEN INGESTED BY THE HOUSE FLY UNDERGO ANY DE-
VELOPMENT, OR DOES IT REMAIN LONG ENOUGH UNCHANGED IN ITS
ALIMENTARY TRACT, SO THAT LATER IT MAY BE PASSED OUT IN
ITS EXCRETA ON TO THE SKIN OF A SUSCEPTIBLE PERSON ?

     In order to carry out this experiment, flies (Musca nebulo and Musca sp.)
were bred out from larvæ and kept in suitable cages; they were then taken out in
small numbers in large glass tubes, and allowed to feed on the sore, just at the
time when it was discharging parasites. They were next placed in a clean jar
and examined at regular intervals; many of the flies were repeatedly fed.

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