on
of what are known as antitoxins, and no more wonderful discovery has
ever been made. To understand as best we may the principle involved, it
is necessary to explain the process of bacterial attack. When bacteria
capable of producing disease are introduced into the system, either
through the mouth or into the lungs or into the blood through some skin
abrasion, the bacteria, finding there a congenial habitat, thrive, grow,
and multiply. In some cases, this bacterial growth results only in
breaking down the cell tissues at the point or in the vicinity of the
place where growth occurs; for instance, if a cut is made with a dirty
knife, that is, one carrying bacteria on the blade, and is not
immediately washed out with an antiseptic solution, bacteria will grow
and pus will form in the cut. Similarly, a splinter, if not removed and
cleansed, will produce a pus-forming wound. But unless a very extensive
suppuration starts, the difficulty is all local. So it is with
consumption, when the bacteria are localized in the lungs and by their
growth destroy the lung tissue without, at least for many weeks,
affecting the general health.

There are germs, however, like typhoid fever and diphtheria, which do
not produce any particular local disturbance with the growth of
bacteria, but the whole body becomes sick, the circulation of the blood
is affected, and a general disturbance ensues. This is due to the action
of a poison, called a toxin, which is set free as a result of the growth
of the bacteria in some one part of the body, which poison is then
carried by the blood throughout the entire system, inducing fever and a
general debility.

Just how these toxins are formed is not certain. They are not the
bacteria themselves. This we know because the disease-producing bacteria
can be grown in broth and the mixture can be strained through fine
porcelain, fine enough to strain out the bacteria. Yet it has been found
that the clear liquid passing the porcelain filter is capable of
producing disease and is a deadly poison without the presence of any
bacteria at all. During the incubation period of a disease, as, for
example, in the three-week period when typhoid fever is developing,
these poisons are being formed and are being scattered through the body,
and it is during this time that the fight takes place between these
poisonous forces and the defending forces always present in the human
system. As already pointed out, these defensive