28 LOSS THROUGH INSECTS THAT CARRY DISEASE. 
activity and prevalence of the common house fly is shown not only 
by repeated observations but also by an interesting plotting of the 
curve of abundance of flies in comparison with the plotted curve of 
abundance of death- from intestinal diseases, indicating that the 
greatest number of flies occurred in the weeks ending duly 27 and 
August 3; also, that the death- from intestinal diseases rose above 
the normal at the same time at which Hies became prevalent, culmi- 
nated at the same high point, and fell off with slight lag at the 
time of the gradual falling off of the prevalence of the insect-. 
Similar studies have been carried on during tin- summer of 1008 
in the city of Washington, and the curve of typhoid-fly abundance 
for the whole city, as well as that for a district comprising eight city 
squares in which intensive studies have been made both of flies and 
of disease, will be plotted at the close of the season. At the time 
of present writing this work has not been completed. 
The typhoid fly also possesses import a nee as a disseminator of the 
bacilli of tuberculosis. In a paper by Dr. Frederick T. Lord, of 
Boston, reprinted from the Boston Medical and Surgical Journal for 
December 15, 1904, pages 651-654, the following conclusions are 
reached : 
" 1. Flies may ingest tubercular sputum and excrete tubercle ba- 
cilli, the virulence of which may last for at least fifteen day-. 
"2. The danger of human infection from tubercular flyspecks is 
by the ingestion of the specks on food. Spontaneous liberation of 
tubercle bacilli from flyspecks is unlikely. If mechanically dis- 
turbed, infection of the surrounding air may occur. 
"As a corollary to these conclusions, it is suggested that — 
" 3. Tubercular material (sputum, pus from discharging sinuses, 
fecal matter from patients with intestinal tuberculosis, etc.) should 
be carefully protected from flies, lest the} 7 act as disseminators of the 
tubercle bacilli. 
" 4. During the fly season greater attention should be paid to the 
screening of rooms and hospital wards containing patients with 
tuberculosis and laboratories where tubercular material i- examined. 
" 5. As these precautions would not eliminate fly infection by 
patients at large, foodstuffs should be protected from flies which may 
already have ingested tubercular material." 
From all these facts it appears that the most important part played 
by the typhoid fly or house fly in the human economy is to carry 
bacteria from one place to another. The following tabic and com- 
ments are taken from Bulletin Xo. 51 (April. 1908), of the Storrs 
Agricultural Experiment Station. Storrs, Conn., entitled " Sources of 
Bacteria in Milk." bv W. M. Esten and C. J. Mason: 
