140 NEW YORK) (ZOOLOGICAL. SOGCIE EN: 
site. The disease has been successfully transferred by innocula- 
tion, as proved by experiments on calves, dogs, and rabbits by 
Johne, Crookshank and others. 
Diagnosis.—Actinomycosis is an unusually easy disease to rec- 
ognize, particularly on account of the characteristic lesions, and 
to the presence of quantities of yellowish or grayish granules rep- 
resenting clusters of actinomyces “ray fungus” which are present 
in the pus and liquid from the suppurating lesions. The organism 
grows in the form of little rounded masses resembling grains of 
iodoform, or as a result of calcareous deposit, grains of sand. 
Upon superficial examination, especially when the disease is 
generalized, and the liver and lungs are involved, actinomycosis 
may be confounded with tuberculosis. In these cases microscopic 
examination makes certain the diagnosis. 
Demonstration of the Parasite——The organism appears in the 
pus from sub-acute or chronic suppurative lesions as grayish or 
yellowish granules, usually less than 1 mm. in diameter. These 
granules are friable, and when gently crushed beneath a cover- 
glass and examined under the microscope, they are seen to have 
been broken up into hyaline rounded masses, at the margins of 
which are fine radial striations or filaments of bulbous or club- 
shaped cells, all closely set together. 
It is owing to this characteristic arrangement of the filaments 
that the name “ray fungus” is applied. The club-shaped bodies 
are variable in size, and are composed of a hyaline substance. Not 
all of the granules have these “clubs.” In the granules obtained 
from the lesions of wild animals—antelope—they are much 
less frequently observed than in those obtained from the lesions in 
cattle. 
Contrasted with the frequency of actinomycosis in the head, 
that of other organs is comparatively rare. 
Actinomycosis of the jaw bones frequently attacks young ani- 
mals, and its usual seat is in the region of the molar teeth, (Plate 
Il) although it occasionally affects the incisors. The earliest 
change consists of a swelling of the bone, generally in the middle 
region of the row of molars. This swelling, which is at first 
firm and painful to the touch, gradually increases in size, invades 
the deeper regions of the skin, and is followed by the formation 
of abscesses which soon show points of fluctuation. These ab- 
scesses opening on the surface, discharge a whitish, creamy, 
odorless pus. The cavity of the abscess shows no tendency 
toward healing, and the opening through which the pus has 
escaped is transformed into a fistula. (Plate I.) Later on, the 
