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 6// 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. 



