e army. It is
therefore apparent that during a war, disease, unless quickly checked,
may run like wild fire through a country, and be disseminated far and
wide by soldiers returning to and from their own homes, or other
distant places while on leave.

Advances made in our knowledge of how diseases are spread and
controlled, particularly through recent studies in bacteriology and
immunity, have made it possible to keep communicable diseases in
absolute subjection. The marvel of the age is the lack of epidemic
disease in the army to-day. This is particularly striking in view of
our experiences in other recent wars. In the Franco-Prussian war of
1870, for instance, smallpox was fanned into a great flame, and there
resulted the largest smallpox epidemic in 80 years. It is interesting
to note that the medical authorities in Paris, in the first year and a
half of the present war, vaccinated over 25,000 strangers passing
through Paris; they are taking no chances with another outbreak of
smallpox.

In the Boer War the British losses through typhoid fever alone were
8,000 against 7,700 killed by bullets, shells and other agencies.

The British army of nearly five million men in France and England
to-day, has so little typhoid that it is practically a negligible
quantity, and this holds with other communicable diseases. There must
be some basic reason for this freedom from contagious diseases, for we
know that such freedom does not come by accident.

No attempt will be made to deal with those auxiliary forces employed
to keep the men physically and mentally fit. Such things as the
provision of an adequate and wholesome food supply; proper clothing;
amusements, such as games, competitions, horse shows, cinemas, variety
shows; and Y.M.C.A.'s are all an integral part of the machinery
necessary to keep an army in the field well and happy.

Only an attempt will be made to discuss the principles underlying the
prevention of disease in use in the British army in France,--principles
with which the average layman is comparatively unacquainted.

In the first place, it is well to realize that in the temperate
climate of Europe, the vast majority of communicable diseases of
importance from the military standpoint are contracted largely from
three sources:

Group 1. From throat and nose secretions; e.g., diphtheria, measles,
etc.

Group 2. From biting insects; e.g., malaria, typhus fever, plague,
etc.

Group 3. Through intestinal