ACTINOMYCOSIS. ° 81 
way ; or they may be scraped, and the scrapings spread 
on a slide. Sections may also be cut, but are not 
usually necessary for the diagnosis. 
EXAMINATION OF THE SPECIMENS. 
Actinomycosis is caused by the ray-fungus, an organ- 
ism which derives its name from the star-shaped 
colonies which it forms whilst growing in the tissues. 
It consists of two chief parts; the central portion of the 
colony is formed of a network of narrow filaments, which 
have a radial arrangement at the periphery (Plate II., 
fig. 6). In this part small bodies which have the appear- 
ance of cocci may often beseen. The outer zone consists 
of the clubs which (when present) are so characteristic. 
These clubs are flask-shaped expansions of the sheath 
of the radial filaments already mentioned, and are 
arranged with their narrow extremities pointing in- 
wards. They are not generally present in man, and 
when present are often badly developed; they are much 
more common and more perfect in the ox, where the 
disease is more chronic, and pus formation rare. 
The films should be carefully examined for the pre- 
sence of these structures. Clubs are not likely to be 
found in the pus, and their absence does not tell against 
the diagnosis; the dense felted network of filaments 
retaining Gram’s stain is what is to be looked for, 
and its presence is quite sufficient for a diagnosis. 
Fortunate specimens may show a complete colony, with 
its irregular network in the centre and the radial ar- 
rangement of the fibres on the periphery, or there may 
be mere fragments of mycelium. 
