STEUCTUEE, DEVELOPMENT, AND BIONOMICS OP HOUSE-FLY. 389 
tremely sensitive to tlie change of temperature, and that the 
cold nights kill them off rapidly.” In the discussion on this 
paper Church stated that “many nurses told me that if one 
went into a tent or ward in which the patients were suffering 
from a variety of diseases, one could tell at once which were 
the typhoid patients by the way in which the flies clustered 
about their mouths and eyes while in bed.” It was further 
stated in the discussion that where the Americans used quick- 
lime in their latrines the cooks in the neighbouring kitchens 
found that the food became covered with quicklime from the 
flies which came from the latrines to the kitchens. 
Dr. Tooth, in a letter to me, says : “ I am afraid my written 
remarks hardly express strongly enough the importance that 
I attach to flies as a medium of spreading infection. Of course 
I do not wish to under-rate the water side of the question, 
but once get, by that means, enteric into a camp the flies, in 
my opinion, are quite capable of converting a sporadic incidence 
into an epidemic. A pure water supply is an obvious necessity, 
but the prompt destruction of refuse of every description is 
every bit as important.” 
Smith (1903), in speaking of his experiences in South 
Africa, says that : “ On visiting a deserted camp during the 
recent campaign it was common to find half a dozen or so 
open latrines containing a foetid mass of excreta and maggots.” 
Similar observations were made by Austen (1904), who, de- 
scribing a latrine that had been left a short time undisturbed, 
says : “A buzzing swarm of flies would suddenly arise from it 
with a noise faintly suggestive of the bursting of a percussion 
shrapnel shell. The latrine was certainly not more than one 
hundred yards from the nearest tents, if so much, and at meal- 
times men’s mess-tins, etc., were always invaded by flies. A 
tin of jam incautiously left open for a few minutes became a 
seething mass of flies (chiefly Pycnosoma chloropyga 
Wied), completely covering the contents.” 
Howard (1900) referring to an American camp, where no 
effort was made to cover the faeces in the latrines, says : “ The 
camp contained about 1200 men, and flies were extremely 
