ACTINOMYCOSIS 261 
charge of pus must be severe. Mayo reports several cases where the 
disease was watched for five or six years and where it would possibly 
have continued several years more had not the animals been destroyed. 
Most animals which become affected with actinomycosis are either 
destroyed, treated or slaughtered for beef. 
Morbid anatomy. The new actinomycotic growths have in or near 
their centers rosettes of the ray fungus surrounded usually by giant 
cells. These in turn are surrounded by tissue consisting principally 
Fic. 57. A DRAWING OF AN ACTINOMYCOTIC JAW. 
of epithelioid and spindle shaped, connective tissue cells, among which 
giant cells may appear. As these cells increase in number they press 
against the surrounding tissues, thus producing the hard and dense 
tumor-like growths. This is especially true when they are located in 
the connective tissue. In certain other positions, such as the liver, 
the inflammatory cells are surrounded by a fibrous tissue frame-work 
which gives to the lesion a honeycomb appearance. On section a dis- 
agreeable “nutty”’ odor is given off which Mayo considers to be quite 
characteristic of the disease. The outside of the tumor is usually 
composed of a dense layer of fibrous connective tissue. Extending 
from the periphery toward the center, the tissue becomes less dense 
and is composed largely of epithelioid cells. In the softer tissue 
there are often cavities of greater or less size filled with a viscid, 
purulent substance in which the small, yellowish granules, “rosettes,” 
