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Bagdad, so that unless a sore had developed at the exact spot the 
experiment would he valueless and even had a sore developed there, 
there would be the possibility of some other Hy having bitten and 
produced the sore. Still the failure of the Stegomyia to produce an 
infection seems to give some evidence against its being the natural host 
of the sore parasite. It would have been better had more than twelve 
days elapsed between the first feed from the sore and the feeding on 
myself, but it is only possible to form a single experiment on oneself, and 
the difficulty of finding persons suitable or willing for such experiments, 
prevented them being extended. The experiment is interesting in so 
far that it has given a negative result. 
J. Origin of the Disease. 
There are many local hypotheses regarding the origin of the sore. 
Some people maintain that it is only those who drink the water of the 
Tigris or Euphrates who become infected; others that it is due to the 
contamination of open sores or wounds by dirt from the roads, while 
others think it is in some way related to syphilis. The names “ date 
boil ” and “ date mark ” are attributable to the view that the disease 
is due to the dates which become ripe at the season of maximum 
incidence of the sore. None of these hypotheses will explain the disease. 
The peculiar distribution of the sore on the exposed surfaces of the body, 
the character of the specific parasite and the development of this parasite 
into Herpetoraonas forms in the culture tube can only be accounted for 
by the assumption that there is some fly responsible for the transmission 
of the sore. The possibility of the house-fly acting as a mechanical 
carrier of the disease has been mentioned above. It is almost certain 
that the house-fly from time to time plays the part of such a mechanical 
carrier and transfers some of the parasites from an open sore to a fresh 
and healthy wound. The parasites may be carried over in moist 
material adhering to the proboscis or feet of the fly. That this 
mechanical transmission by the house-fly is to be regarded as the 
normal means of infection cannot be maintained, for it is certain that 
sores appear on parts of the skin where there have been no wounds or 
abrasions. It is improbable that the mere application of juice from a 
sore to the healthy skin will give rise to an infection, though it would 
be of interest to test this point experimentally. Even if it were possible 
for the mobile cultural forms of the sore parasite to pass through the 
uninjured skin, it is difficult to imagine how the passive immobile forms 
