PATHOGENIC BACTERIA. 



299 



Actinomyces bovis 1 ( Streptothrix actinomyces, Ray- fun- 

 gus of actinomycosis). The morphology of this organism 

 is quite different from that of most of the bacteria. It is 

 sometimes considered to be a bacterium of a higher type. 

 The organism appears in the form of threads which show 

 genuine branching. These threads make radiating, inter- 

 lacing masses. Their external ends are swollen and bulbous 

 under certain conditions. Colonies formed in this manner, 

 seen under moderate mag- 

 nification, have a radiat- 

 ing appearance which has 

 given rise to the name, 

 ray-fungus. The club- 

 shaped external ends are 

 readily distinguished and 

 the growth possesses a 

 very distinctive form. 

 This is the shape which 

 the organism presents as 

 it grows in the animal 

 body. The club-shaped 

 ends are generally re- 



1 i i Ray-fungus of Actinomycosis. Fresh, 



garded as a degener- 



unstained preparation from a case of 



ative Or involution form. l ump .j aw in a cow . Diagrammatic. 



Transverse divisions may 



sometimes be distinguished upon the threads. Spherical 

 forms resembling micrococci may appear which may pos- 

 sibly be spores. In some members of this group spores 

 form in cultures on the ends of the filaments (conidia). 

 The organism stains with the ordinary aniline dyes, by 

 Gram's method or the Weigert fibrin stain. 



The fungus may be cultivated upon the usual culture- 

 media, though not easily. It is facultative anaerobic. It 



1 Hektoen, Philadelphia Monthly Medical Journal, November, 1899; 

 Ewing, Bulletin Johns Hopkins Hospital, November, 1902. 



