Is a chronic contagious disease of cattle, "lumpy jaw," but is sometimes found in man.

Is caused by a fungus, probably a streptothrix, the Actinomyces bovis, which is large enough to be seen by the naked eye, appearing as small yellow particles. The fungus is made up of a central mass of granular substance in which there are many structures resembling chains of cocci or spores. Extending from this center are many mycelial threads terminating in club-shaped extremities. Is both aerobic and anaerobic in its growth; was formerly thought that the latter form alone was pathogenic. Will grow on any artificial media.

Stains yellow with picric acid, red with picrocarmin, blue with anilin gentian and by Gram's.

The infection is supposed to take place by means of spores gaining entrance into the human system by means of food or by inhalation. Probably enters by way of decayed teeth or through abrasions of the mucous membrane.

Where the fungus lodges there is a formation of nodules which break down, form abscesses, and discharge a creamy pus containing yellowish granules; which show the characteristic rayed appearance when looked at under the microscope.

The neighboring bones may become riddled with sinuses and there may also be metastatic growths in other organs, particularly the lungs. In the latter extensive necrosis may occur, with the formation of small cavities containing pus and fragments of degenerated tissues, and the fungus will be found in the sputum.

Instead of breaking down, connective tissue may be formed and encapsulate the invaded area.

Microscopically there is found a granulation tissue containing large masses of lymphoid cells, a few epithelioid cells, and giant cells resembling closely a tubercle.

Fig. 34. - Actinomyces Cluster Showing Radial Striations at Periphery (Karg and Schmorl).