THE TYPHOID PLY, OB HOUSE PLY. 25 
origin of the fever was confirmed. The conclusion was reached thai 
the fever is disseminated by the transference of the excretions of an 
infected individual to the alimentary canals of others, and that a 
man infected with typhoid fever may scatter the infection in every 
Latrine or regiment before the disease is recognized in himself, while 
germs may he found in the excrement for a lone,- time after the 
apparently complete recovery of the patient. Infected water was 
not an important factor in the spread of typhoid in the national 
encampments of 1898, hut aboul one-fifth of the soldiers in the 
national encampments in the United States during that summer de- 
veloped this disease, while more than SO per cent of the total deaths 
were caused by typhoid. 
In L899 the writer began the study of the 1 typhoid or house fly 
under both country and city conditions. lie made a rather thorough 
investigation of the insect fauna of human excrement, and made a 
further investigation of the species of insects that are attracted to 
food supplies in houses. Tn a paper entitled "A Contribution to the 
Study of the Insect Fauna of Human Excrement (with special refer- 
ence to the spread of typhoid fever by flies)," published in the Pro- 
ceedings of the Washington Academy of Sciences, Volume II, pages 
r>41-c>04, December 28, 1900, he showed that 98.8 per cent of the whole 
number of insects captured in houses throughout the whole country 
under the conditions indicated above were Musca domestica, the 
typhoid or house fly. He showed further that this fly, while breeding 
most numerously in horse stables, is also attracted to human excre- 
ment and will breed in this substance. It was shown that in towns 
where the box privy was still in existence the house fly is attracted to 
the excrement, and, further, that it is so attracted in the filthy regions 
of a city where sanitary supervision is lax and where in low alleys 
and corners and in vacant lots excrement is deposited by dirty people. 
He stated that he had seen excrement which had been deposited over- 
night in an alleyway in South Washington swarming with flies under 
the bright sunlight of a June morning (temperature 92° F.), and that 
within 30 feet of these deposits were the open windows and doors of 
the kitchens of two houses kept by poor people, these two houses 
being only elements in a long row. The following paragraph is 
quoted from the paper just cited : 
" Now. when we consider the prevalence of typhoid fever and that 
virulent typhoid bacilli may occur in the excrement of an individual 
for some time before the disease is recognized in him, and that the 
same virulent germs may be found in the excrement for a long time 
after the apparent recovery of a patient, the wonder is not that ty- 
phoid is so prevalent but that it doe.-> not prevail to a much greater 
