the seat of puncture. If the bulk of the full dose is large, it should
be divided and injected into different parts of the body, not more than
20 c.c. being injected at one place. The serum may be introduced
directly into a vein, or into the spinal canal, _e.g._ anti-tetanic
serum. The immunity produced by injections of antitoxic sera lasts only
for a comparatively short time, seldom longer than a few weeks.

_"Serum Disease" and Anaphylaxis._--It is to be borne in mind that some
patients exhibit a supersensitiveness with regard to protective sera, an
injection being followed in a few days by the appearance of an
urticarial or erythematous rash, pain and swelling of the joints, and a
variable degree of fever. These symptoms, to which the name _serum
disease_ is applied, usually disappear in the course of a few days.

The term _anaphylaxis_ is applied to an allied condition of
supersensitiveness which appears to be induced by the injection of
certain substances, including toxins and sera, that are capable of
acting as antigens. When a second injection is given after an interval
of some days, if anaphylaxis has been established by the first dose, the
patient suddenly manifests toxic symptoms of the nature of profound
shock which may even prove fatal. The conditions which render a person
liable to develop anaphylaxis and the mechanism by which it is
established are as yet imperfectly understood.

_Vaccine Treatment._--The vaccine treatment elaborated by A. E. Wright
consists in injecting, while the disease is still active, specially
prepared dead cultures of the causative organisms, and is based on the
fact that these "vaccines" render the bacteria in the tissues less able
to resist the attacks of the phagocytes. The method is most successful
when the vaccine is prepared from organisms isolated from the patient