2IO ACTINOMYCOSIS 



unaided eye. These pus cavities are usually connected with 

 each other by small sinusts but sometimes they are separated 

 bv bands of fibrous tissue. 



Fig. 45. Head of a steer with actinomycosis of the lower jaw. 

 {Photographed by Hopkins. ) 



If the disease is in the bone, usually in the head, as it is 

 where the specific organism gains entrance and begins to grow 

 in the interior of the bone, the bone tissue about the organism 

 becomes in places disintegrated and absorbed and pockets are 

 formed containing the fungus. While the interior of the bone 

 is being broken down and absorbed by the action of the acti- 

 nomycotic growth within, its diameter is being increased by 

 the deposition of new tissue until it may become several times 

 its normal size. 



The disease spreads within the body in most cases by 

 gradual invasion of the tissues surrounding the infected point. 

 At the seat of infection, minute, inflammatory points appear 

 which extend at their periphery and unite to form larger areas 

 of diseased tissue. These masses tend to extend in one direc- 

 tion and to heal in another leaving behind bands of cicatricial 



