disease.

Fig. 2. Actinomyces fungus from a tumor of the jawbone in cattle, magnified
550 times.

PLATE XL. Actinomycosis of the jaw. (Reduced one-half. From Joehne's
Encyklopaedie d. gesammt. Thierheilkunde.) The lower jaw is sawed through
transversely, i.e., from right to left, and shows the disease within the
jawbone itself; _a_, within the mouth, showing the papillae on the mucous
membrane of the cheek; _b_, front view of a molar tooth; _c_, the skin
covering the lower surface of the jawbone; _d_, the jawbone hollowed out
and enlarged by the formation of cavities within it, which are filled with
the soft growth of the actinomycotic tumor. The section makes it appear as
if the bone were broken into fragments and these forced apart; _e_, a
portion of the tumor which has broken through the bone and the skin and
appears as a tumor on the cheek. The little roundish masses represent the
granulomata (minute tumors) in which the fungus vegetates.

PLATE XLI. Actinomycosis of the lungs.

Fig. 1. Transverse section of the ventral lobe of the right lung, from a
case studied in the laboratory. The yellowish dots represent the places
where the actinomyces fungus is lodged. The larger yellowish patches are
produced by the confluence of a number of isolated centers. The entire lobe
is of a dark flesh-red color, due to collapse and bronchopneumonia.

Fig. 2. The cut surface of a portion of the principal lobe of the same
lung, showing the recent invasion of antinomycosis from the other lobe:
_a_, large air tube; _b_, artery; _c_, a pneumatic lobule; _d_, lobule
containing minute yellowish dots. In these the actinomyces fungus is
lodged.

Fig. 3. Cut surface of a small portion of another lung, showing a few
lobules, _a._ The fungus is sprinkled throughout the lung tissue in the
form of yellowish grains, as shown in the illustration. The pleural
covering of the lung tissue is shown in profile above.

[Illustration: PLATE XXXIX.
Fig. 1
Fig. 2
ACTINOMYCOSIS.]

[Illustration: PLATE XL. ACTINOMYCOSIS OF THE JAW.]

[Illustration: PLATE XLI.
Fig. 1
Fig. 2
Fig. 3
ACTINOMYCOSIS OF THE LUNGS.]

* * * * *

_Cause._--The cause of anthrax is a microscopic organism known as the
anthrax bacillus. (See Pl. XXVIII, fig. 7.) In form it is cylindrical or
rodlike, measuring 1/5000 to 1/2500 inch in length and 1/25000 inch in
diameter. Like all bacteria, these rodlike bodies have t