ACTINOMYCOSIS. 187 



club-like termination, the whole mass having very much the 

 appearance of a rosette. Sometimes the free ends of the 

 thread are only slightly or not at all swollen (Fig. 69). The 

 threads which compose the centre of the mass are from 0.3 

 to 0.5 mikron in width. The clubs are from 0.6 to 0.8 

 mikron in width. These mycelia stain by all the ordinary 

 anilin colors, and also by Gram's method, though by these 

 methods their fine structure is not always brought out. The 

 best stain for the fungus is Mallory's stain, which is as fol- 

 lows : 



Stain the secretions on the slide with gentian-violet, dehy- 

 drate, and clear with anilin oil to which a little basic fuchsin 



FIG. 69. 



Actinomycosis fungus in pus. Fresh, unstained preparation. Magnified 

 about 500 diameters. (Abbott.) 



has been added, and mount in xylol balsam. In this way 

 the cocci in the centre and the threads of the mycelium are 

 stained blue ; the club-like extremities are stained red. 



Biologic Characters. The Streptothrix actinomyces grows in 

 all the ordinary artificial media, but from the fact that all 

 the mycelia seen under the microscope are not living, it is 

 often necessary to make several cultures before obtaining a 

 satisfactory one. It grows both with and without oxygen, 

 either at the room temperature or at the temperature of the 

 incubator, and is not resistant to heat, being destroyed by a 

 temperature of 75 C. in five minutes. 



