324 ACTINOMYCOSIS AND ALLIED DISEASES 



by Gram's method. Occasionally in very chronic lesions in the 

 human subject the clubs stain with Gram's method. Clubs 

 showing intermediate staining reaction have been described in 

 the ox by McFadyean. The club formation probably represents 

 a means of defence on the part of the parasite against the 

 phagocytes of the tissue ; the view, formerly held, that the clubs 

 are organs j of fructification has now been generally abandoned. 





Fig. 92. — Colonies of actinomyces, showing general structural 

 arrangement and clubs at periphery. From pus in human subject. 

 Stained by Gram's method and safranin. x 60. 



In the majority of cases in the ox no filaments can be detected 

 in the colonies, and it is from such colonies that Lignieres and 

 Spitz have cultivated the actinobacillus. 



Tissue Lesions. — In the human subject the lesions are of a 

 chronic inflammatory type, usually ending in a spreading sup- 

 puration. In some cases there is a comparatively large pro- 

 duction of granulation tissue, with only a little softening in the 

 centre, so that the mass feels solid. In most cases, however, 

 and especially in internal organs, suppuration is the outstanding 

 feature ; this is associated with abundant growth of the parasite 



