538 TRICHOMYCETES, ACTINOMYCETES, HYPHOMYCETES 



Actinomyces bovis stains by Gram's method, but the clubs are not 

 colored. Eosin brings them out clearly. It has been held by Bostrom 1 

 that the clubs are degenerative phenomena, but Wright 2 believes their 

 chief function is a protective one, shielding the filaments from the 

 harmful action of the body fluids and cells of the host. 



Isolation and Culture. The organism is anaerobic and appears to 

 grow with moderate luxuriance in deep glucose-agar stab cultures. 

 Material for inoculation is best obtained by crushing a granule between 

 sterile glass slides, or rubbing it on the inside of a sterile test-tube, 

 after two to three preliminary washings in sterile salt solution to 

 remove or diminish surface contamination. The finely macerated 

 colony is distributed evenly in deep dextrose-agar tubes and incubated 



FIG. 82. Actinomyces club formation, semi-diagrammatic. 



at 37 C. After two to five days colonies appear scattered through 

 the depths of the medium and are generally very numerous in a zone 

 0.5 to 1 cm. below the surface. They do not ordinarily grow above 

 this level. The deeply lying colonies increase in size until they 

 measure 1 to 3 mm. in diameter at the end of a week's incubation. 

 Microscopically these colonies consist of masses of radially arranged, 

 branching filaments which exhibit a decided tendency to break up 

 into short bacilloid or ovoid segments. A colony at this stage becomes 

 a mass of compact short filaments and bacillary forms. Clubs are not 

 seen under these conditions unless blood or blood serum is added to 

 the medium. 



In bouillon the organisms grow in dense white or gray masses of 



1 Beitr. z. path. Anat., u. z. allg. Path., 1890, ix, 1. 



2 Loc. cit., p. 397. 



