CHARACTERS OF THE ACTINOMYCES 289 



filaments and the spherical bodies are readily stained by 

 Gram's method. 



3. Clubs. These are elongated pear-shaped bodies which are 

 seen at the periphery of the colony, and are formed by a sort of 

 hyaline swelling of the sheath around the free extremity of a 

 filament (Figs. 97, 98). They are usually homogeneous and 

 structureless in appearance. In the human subject the clubs are 



FIG. 97. Actinomyces in human kidney, showing clubs radially arranged 



and surrounded by pus. The filaments had practically disappeared. 



Paraffin section ; stained with hsematoxylin and rubin. x 500. 



often comparatively fragile structures, which are easily broken 

 down, and may sometimes be dissolved in water. Sometimes 

 they are well seen when examined in the fresh condition, but in 

 hardened specimens are no longer distinguishable. In specimens 

 stained by Gram's method they are usually not coloured by the 

 violet, but take readily a contrast stain, such as picric acid, 

 rubin, etc ; sometimes a darkly-stained filament can be seen 

 running for a distance in the centre, and may have a knob-like 

 extremity. In many of the colonies in the human subject the 

 clubs are absent. In the ox, on the other hand, where there are, 

 19 



