PATHOGENIC BACTERIA. 



367 



branching. These threads make radiating, interlacing masses. 

 Their external ends are swollen and bulbous under certain 

 conditions. Colonies formed in this manner, seen under 

 moderate magnification, have a radiating 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 regarded as a degenerative or involution 



Fig. 93. — Ray-fungus of actinomycosis. Fresh, unstained preparation 

 from a case of lump-jaw in a cow. {Diagrammatic.) 



form. Transverse divisions may sometimes be distinguished 

 upon the threads. Spherical forms resembling micrococci 

 may appear which may possibly be spores. In some members 

 of this group spores— conidia— form in cultures on the ends 

 of the filaments. While the organism stains with the ordinary 

 aniline dyes, by Gram's method or the Weigert fibrin stain. 

 It is absolutely essential that the anilin oil-gentian violet be 

 prepared with a strictly saturated alcoholic solution of gentian 

 violet, and that the stain should be a few days old, not freshly 

 prepared.* 



*Giinther. Loc. cit. p. 780. 



