ACTINOMYCOSIS. 8l 



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 be seen. 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. 



