CHARACTERS OF THE ACTINOMYCES 



323 



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. 91, 92). They are usually homogeneous and 

 structureless in appearance. In the human subject the clubs are 

 often comparatively fragile structures, which are easily broken 

 clown, and may sometimes be dissolved in water. Sometimes 



Fig. 91. — Actinomyces in human kidney, showing clubs radially 

 arranged and surrounded by iius. The filaments had practically 

 disappeared. 



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



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 

 much older colonies, the clubs constitute the most' prominent 

 feature, and often form a dense fringe around the colony, staining 



