Morphology 



377 



tangled mass of mycelial threads. In an outer zone these 

 threads are seen to terminate in conspicuous, club-shaped, 

 radiating forms which give the colonies their rosette-like 

 appearance. The clubs are inconspicuous in the human 

 lesions of the disease. 



The pleomorphism of the organism and the branched 

 network it forms class it among the higher bacteria in the 

 genus Actinomyces. When the clumps formed in artificial 

 cultivations of the parasite are properly crushed, spread 



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V 



Fig. 108. Colony or granule of actinomyces in a section through a 

 lesion, showing the Gram-stained filaments and hyaline material ana 

 also the pus-cells surrounding the colony (Wright and Brown). 



out, and stained, the long mycelial threads, 0.3-0.5 // in 

 thickness, frequently show flask- or bottle-like expansions 

 the clubs at the ends. These probably depend upon 

 gelatinization of the cell-membrane of the degenerating 

 parasite. 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, 

 closely packed together, and making the whole mass form 



