STEUCTUEE, DEVELOPMENT, AXD BIONOMICS OF HODSE-FLY. 385 
1. Typhoid Fever. 
Of all infectious diseases the conditions in this are most 
favourable for the transference of infection by M. dom estica, 
and it is no doubt on this account that the greatest attention 
has been paid to the role of house-flies in the dissemination 
of this disease. The chief favourable condition is that the 
typhoid bacillus occurs in the stools of typhoid and incipient 
typhoid cases. Human excrement attracts flies not only on 
account of its moisture but as suitable food for the larvae. 
The infected excrement is often accessible to flies, especially 
in military camps, as will be shown shortly, and the flies also 
frequent articles of food and not infrequently the moist lips of 
man. Such are the conditions most suitable for the transfer- 
ence of the bacilli, and it is on account of the frequent 
coincidence of these conditions that flies can play, and have 
played, such an important role in the dissemination of this 
disease among communities, in spite of the fact that the 
typhoid bacillus cannot survive desiccation, which I think is 
an argument against its being carried by dust. 
Epidemiological and other evidence. — There is a 
very large amount of testimony given as to the role played 
by flies in the spread of enteric in military stations and camps, 
and especially during the two wars — the Spauish-American 
and the Boer War. All the conditions most favoui’able for 
the dissemination of the bacilli by flies were, and in many 
military stations are still, present; open latrines or filth- 
trenches accessible to flies on the one hand and on the other 
the men’s food within a short distance of the latrines. I 
cannot do better than repeat the evidence in the words of the 
witnesses and allow it to speak for itself. 
Vaughan, a member of the U.S. Army Typhoid Commis- 
sion of 1898, states d 
“ 51y reasons for believing that flies were active in the dis- 
semination of typhoid fever may be stated as follows : 
* In a paper, " Conclusions Reached after a Study of Tj^ihoid Fever 
amont' American Soldiei*s.'' read before the American Medical Asso- 
ciation at Atlantic City, N.J., in lyuu. 
