582 MICROBIOLOGY OF THE DISEASES OF MAN AND ANIMALS. 



Actinomyces bovis grows rapidly on a variety of laboratory media. On gylcerin 

 agar the colonies develop into transparent drop-like bodies in four or five days at 37. 

 Old colonies become white or yellowish with a powdery surface. The cultural 

 and other peculiarities vary much and according to the variety under observation, 

 Some varieties appear distinctly aerobic and others anaerobic. As a rule it liquefies 

 gelatin growing in spherical masses which settle to the bottom of the liquid. Filaments 

 appear in artificial growth which are very long and slender, and about 6fi in diameter. 

 They show true branching, but have no septa (Fig. 99). The young colony is a 

 loose mass of filaments; older colonies become dense and felted. Rod-shaped and 

 spherical forms appear in artificial cultures, and some filaments develop conidia. 





FIG. 99. Actinomycosis. Actinomyces bovis. Preparation from a pure culture. X 



1000. (After Williams.) 



Stains easily. Tissue section stained with carmine followed by Gram's method gives 

 good results, the thread showing dark and clubs red. Carmine followed by Weigert 

 gives a beautiful stain. May be recognized as visible granules found floating in the 

 pus in case of suppuration, or embedded in tissue. These granules vary in color; 

 some are clear or yellow; others are quite dark. The colony as it appears in tissue 

 section or pus smear consists of a rosette arrangement. The central portion of the 

 colony is a dense mass of mycelium and spherical bodies. From this felted central 

 mass, there extend rays or club-like bodies. Club-shaped enlargements at the ends of 

 filaments frequently appear and are regarded as a distinguishing characteristic of 

 Actinomyces. This organism is usually destroyed at 75 for thirty minutes. Final 

 diagnosis must rest upon actual demonstration under the microscope which is not diffi- 

 cult. The granular masses may be washed in normal salt solution; and examined 

 unstained, or stained in diluted carbol fuchsin. 



