ed. Death from wounds is due more frequently to infection than
to the actual injury represented by the wounds. Much depends upon the
character of the wound. Infection of clean wounds which are made by a
sharp cutting instrument and from which there is abundant haemorrhage
with sealing of the edges of the wound by clotted blood, rarely
happens. Typical wounds of this sort are often made in shaving, and
infection of such wounds is extraordinarily rare. If, with the wound,
pathogenic organisms are placed in the tissue, or foreign substances
such as bits of clothing are carried in with a bullet, for example, or
if the instrument causing the wound be of such a character as to
produce extensive lacerations of tissue, infection is more apt to
occur. The less frequency of infection in modern wars is in part due
to the simpler character of the wounds and in part to the fact that
modern fixed ammunition is practically free from germs. The old
spear-head, the arrow, the cross bow bolt, had little regard for the
probabilities of infection. Whether infection follows a wound depends
both upon the entry of pathogenic organisms and upon these finding in
the tissues suitable opportunities for growth. In wounds in which
there is much laceration of tissue organisms find the most favorable
conditions for development. The very slight wounds produced by the
exploded cap in the toy pistol give suitable conditions for the
development of the bacillus which produces tetanus or lockjaw. The
deaths of children from lockjaw following a Fourth of July celebration
have often exceeded the total deaths in a Central American revolution.
The tetanus bacillus is a widely distributed organism, whose normal
habitat is in the soil and which is usually present on the dirty hands
of little boys. The toy-pistol wounds are made by small bits of paper
or metal being driven into the skin by the explosion of the cap. The
wound is of little moment, the surface becomes closed, and a bit of
foreign substance, a few dead cells and the tetanus bacilli from the
surface remain enclosed and in a few days the fatal disease develops.
Infection of the surfaces of old wounds such as the surface of an
ulcer takes place with difficulty. Large numbers of leucocytes which
give protection by phagocytosis are constantly passing to the surface,
and there is also a constant stream of fluid towards the surface. On
such a surface there may be an abundant growth of pathogenic
organisms, b