e they will
live but a short time, or they may be carried in the alimentary canal
where they will live for a much longer period and are finally deposited
in the fly-specks where they retain their virulence for some time. Flies
that had been allowed to contaminate themselves with cholera germs were
allowed access to milk and meat. In both cases hundreds of colonies of
the germs could later be recovered from the food. As with the typhoid
germs milk seems to be a particularly good medium for the development of
the cholera germs. In several of the experiments that have been made
along this line the milk has been readily infected by the flies visiting
it.

Of course an outbreak of cholera is of rare occurrence in our country,
but unfortunately this is not so in regard to some other intestinal
diseases such as diarrhea and enteritis which annually cause the death
of many children, especially bottle-fed babies. Those who have made
close studies of the way in which these diseases are disseminated are
convinced that the flies are one of the most important factors in their
spread.

It has long been observed that flies are particularly fond of sputum and
will feed on it on the sidewalk, in the gutter, the cuspidor or wherever
opportunity offers. It is well known, too, that the sputum of a
consumptive contains myriads of virulent tubercular germs. A fly feeding
and crawling over such material must necessarily get some of it on its
body, and as it dries and the insect flies about the germs will be
distributed through the air, possibly over our food. It has been shown
that the excretion from a fly that has fed on tubercular sputum contains
tubercular bacilli that may remain virulent for at least fifteen days.
Thus we see again the danger that may lurk in the too familiar
"fly-specks."

Although it is generally supposed that the flea is solely responsible
for the spread of the bubonic plague and no doubt is the principal
distributing agent, the fact must not be overlooked that the house-fly
may also be of considerable importance in this connection. Carefully
planned experiments have shown that flies that have become infected by
being fed on plague-infected material may carry the germs for several
days and that they may die of the disease. During plague epidemics flies
may become infected by visiting the sores on human or rat victims or by
feeding on dead rats or on the excreta of sick patients, and an infected
fly is always a mena