A CTINOM YCOSIS. 263

When the actinomyces are grown upon artificial media
their virulence is retained for a considerable length of
time. If introduced into the abdominal cavities of rab-
bits, there are produced in the peritoneum, mesentery,
and omentum typical nodules containing the actinomyces
rays.

The organism can also be grown in raw eggs, into
which it is carefully introduced through a small opening
made under aseptic precautions. In the egg the organism
forms peculiar long mycelial threads quite unlike the short
forms developing upon agar-agar.

The characteristic rosettes which are constantly found
in the tissues are never seen in artificial cultures.

The exact manner by which the organism enters the
body is unknown. In some cases it may be by direct
inoculation with pus, but there is reason to believe that
the organism occurs in nature as a saprophyte, or as
an epiphyte upon the hulls of certain grains, especially
barley.- Woodhead records a case where a primary me-
diastinal actinomycosis in the human subject was sup-
posed to be traced to perforation of the posterior pharyn-
geal wall by a barley spikelet swallowed by tlie patient.

Cases of actinomycosis are fortunately of rare occur-
rence in human medicine, and do not always occur in
those brought in contact with the lower animals. The
fungi may enter the organism through the mouth and
pharynx, through the respiratory tract, through the di-
gestive tract, or through wounds.

The invasion has been known to take place at the roots
of carious teeth, and is more liable to occur in the lower
than in the upper jaw. Israel reported a case in which
the primary lesion seemed to occur external to the bone
of the lower jaw, as a tumor about the size of a cherry,
with an external opening. In two cases of the disease
observed by Murphy of Chicago both began with tooth-
ache and swelling of the jaw.

When inhaled, the organisms gain entrance to the
deeper portions of the lung, and bring about a suppura-