ACTINOMYCOSIS. 261

localities there are produced considerable enlargements
which are sometimes dense and fibrous (wooden tongue)
and sometimes suppurative. In sections of these nodular
formations small yellowish granules surrounded by some
pus can be found. These granules when viewed beneath
the microscope exhibit a peculiar rosette-like body—the
ray-fungus or actinomyces.

The fungus is of sufficient size to be detected by the
naked eye. It can be colored, in sections of tissue, by
the use of Gram's method, or better by Weigert's fibrin
stain. Tissues pre-stained with carmin, then stained by
Weigert's method, give beautiful pictures.

The entire fungus-mass consists of several distinct
zones embracing entirely different elements. At the
centre of the mass there is found a granular substance
containing numerous bodies resembling micrococci. Ex-
tending from this centre into the neighboring tissue is a
radiating, apparently branched, thickly-tangled mass of
mycelial threads. These threads seem to terminate in
a zone of conspicuous club-shaped radiating forms which
give the colonies the rosette-like appearance. The cells
of the tissues affected and a larger or smaller collection
of leucocytes form the surrounding resisting tissue-zone.

The degree of chemotactic influence exerted by the
organism seems to depend partly upon the tissue affected
and partly upon the individuality of the animal. When
the animal is but slightly susceptible, and when the
tongue is the part affected, the disease is characterized
by the production of enlargement due to the formation
of cicatricial tissue. If, on the other hand, the animal
is highly susceptible or the jaw is affected, the chief
symptom is suppuration, with the formation of cavities
communicating by sinuses.

Before the nature of the affection was understood it
was confounded with various diseases of the bones, prin-
cipally with osteosarcoma.

From the tissues primarily affected the disease spreads
to the lymphatic glands, and not infrequently to the