510 PRINCIPLES OF VETERINARY SURGERY 



sion of a tubercle. The parasitic tuft is in fact surrounded 

 by giant cells, which are drowned in their circumferences 

 with masses of lymphoid elements. The organism in re- 

 acting against the actinomyces constructs a lesion similar 

 to a tubercle. Only the foreign body differs. 



(c) Lesions of the Integ^ument. — The skin may show 

 lesions of chronic inflammation, sometimes to a considerable 

 extent. It is hardened, pasted to the subjacent tissues, 

 cracked and overrun with furrows, which penetrate into 

 the muscular masses, transforming them into fibrous zones. 

 Circumscribed tumors, surrounded with a fibrous capsule, 

 are also found on the surface of the skin. 



(d) Lesions of the Lungs. — In the lungs the tumors are 



Fig. 56. 

 Inferior Maxilla of an Ox Attacked with Actinomycosis. 



of variable size, have well defined limits and are surrounded 

 by a thick, fibrous capsule. They contain a product that 

 readily undergoes purulent transformation and fatty de- 

 generation. At other times the lesions are composed of lit- 

 tle nodules, found only by palpating the organ, but in which 

 the parasite is easily found. On microscopic examination 

 these nodules prove to be constituted of small fibrous masses 

 containing the parasite in their centers, surrounded with 

 giant cells and lymphoid elements. The neighboring air 

 cells are compressed and sometimes filled with red corpus- 

 cles. 



In the liver, the udder, the peritoneum and the pleura 

 the lesions exist in the form of tumors. 



