284 



A CTI NO MYCOSIS. 



granules of dark pigment. In the centre of the colony the 

 filaments interlace with one another, and form an irregular 

 network which may be loose or dense ; at the periphery 

 they are often arranged in a somewhat radiating manner, 

 and run outwards in a wavy or even spiral course. They 

 also show branching, a character which at once distinguishes 



FlG. 74. Actinomycosis ot human liver, showing a colony of the 

 parasite composed of a felted mass of filaments surrounded by pus. 



Paraffin section ; stained by Gram's method and with safranin. x 500. 



them from the ordinary bacteria. Between the filaments 

 there is a finely granular or homogeneous ground substance. 

 Most of the colonies at an early stage are chiefly constituted 

 by filaments loosely arranged ; but later, part of the growth 

 may become so dense that its structure cannot be made out. 

 This dense part, starting excentrically, may grow round the 

 colony to form a hollow sphere, from the outer surface 



