7 yS Actinomycosis 



The clubs are commonly so inconspicuous in the lesions of the hu- 

 man form of the disease as to lead some to suppose that the parasite 

 is of a different species. 



When clumps formed in artificial cultivations of the parasite 

 are properly crushed, spread out, and stained, the long mycelial 

 threads, 0.3-0.5 jj, in thickness, occasionally show flask- or bottle- 

 like expansions— ^the clubs — ^at the ends. These probably depend 

 upon gelatinization of the cell-membrane of the degenerating para- 

 site. The club is one of the chief characteristics of the organism. 

 In sections of tissue the radiating filaments are very distinct, and the 

 terminal clubs are all directed outward and closely packed together, 

 making the whole mass form a rounded little body often spoken of 

 as an "actinomyces grain." When tissues are stained first with 



Fig. 307.' — Actinomyces granule crushed beneath a cover-glass, showing radial 

 striations in the hyaline masses. Preparation not stained; low magnifying 

 power (Wright and Brown). 



carmin and then by Gram's method, the fungous threads appear 

 blue-black, the clubs red. The cells of the tissues affected and a 

 larger or smaller collection of leukocytes form the surrounding 

 resisting tissue-zone. 



The fungus is of suflScient size to be detected in pus, etc., by the 

 naked eye. As it usually has a bright yellow color it is not in- 

 frequently spoken of as a "sulphur grain." 



Cultivation. — The actinomyces fungus may be grown upon arti- 

 ficial culture media, as was first shown by Wolff and Israel, and 

 later by Wright. The method of isolating given by the latter, is 

 as follows: 



"The granules, preferably obtained from closed lesions, are first 

 thoroughly washed in sterile water or bouillon and then crushed and 

 disintegrated between two sterile slides. If one is working with a 



