the sick to the well.

_The bacillus of typhoid._

Unfortunately, the typhoid fever germ is comparatively hardy and is not
so easily killed by unfavorable environment as is the germ of pneumonia,
for instance. It lives in water and in the soil, although probably it
does not increase in numbers in either place. Nor will it live in the
soil or in water indefinitely, and a great deal of study has been
expended in trying to determine just how long typhoid fever germs will
live under different conditions. It has been found, for example, that
drying kills the typhoid bacillus in a few hours, although a few may
survive for days. Experiments have also shown that it cannot leave a
moist surface. It cannot, for instance, jump out of cesspools and drains
and take to flight through the air, conveying the disease.

There is no possibility of contracting typhoid fever because a drain
near the house is being cleaned out, since, so far as is known, the
typhoid fever germ does not get into the air. The direct rays of the sun
will kill typhoid fever germs within a few hours, although the value of
this sort of disinfection is limited, because where typhoid fever germs
are apt to accumulate, the turbidity of the water prevents the
penetration of the sun's rays for more than a few inches.

It has been found that a high temperature kills typhoid fever germs, and
even so moderate a temperature as 160 degrees Fahrenheit is sufficient
to destroy them. This is the principle employed in pasteurizing milk,
since it is assumed, justly, that by raising the temperature of the milk
to 160 degrees Fahrenheit, for ten minutes, it will be possible to kill
any typhoid fever germs present. Boiling, of course, since this involves
a temperature of 212 degrees, will kill the germs, and it is for this
reason that wherever a water is suspected of typhoid pollution, it
should be boiled before being used for drinking. It has been found that
in distilled water, that is, in water where no available food is to be
had, the germs will live about a month, and that in water with organic
matter present, but without other bacteria, this period may be extended
two or three times. In water rich in organic matter, but where other
antagonistic bacteria are also present, the typhoid germs are usually
driven out or killed at the end of three or four days.

It is not unreasonable to expect that at least half of the germs
discharged into a stream will live a week, and if the