140 ^'EW YORK ZOOLOGICAL SOCIETY. 



site. The disease has been successfully transferred by innocula- 

 tion, as proved by experiments on calves, dogs, and rabbits by 

 Johne, Crookshank and others. 



Diagiwsis. — 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 suh-acvite or chronic suppurative lesions r s grayish or 

 yellowish granules, usually less than i 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. Xot 

 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 actinomyeosis 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 

 11) although it occasionally afifects 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 fomiation 

 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 



