Cultivation 433 



a rounded little body often spoken of as an "actinomyces 

 grain." When tissues are stained first with 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 sufficient size to be detected in pus, 

 etc., by the naked eye. It can be colored, in sections of 

 tissue, by the use of Gram's or Weigert's stain. Tissues 

 pre-stained with carmin, then by Weigert's method, show 

 beautifully. 



Fig. 127. Actinomyces granule crushed beneath a cover-glass, 

 showing radial striations in the hyaline masses. Preparation not 

 stained; low magnifying power (Wright and Brown). 



Cultivation. The actinomyces fungus may be grown 

 upon all the artificial culture media, as has been fully shown 

 by Israel,* Wolff, and others. 



To obtain a pure culture, material containing the actino- 

 myces granules, secured so as to be as" free as possible from 

 contaminating micro-organisms, is crushed between glass 

 plates or in a mortar, and the crushed fungi transferred 

 to plates or tubes as desired. The colonies appear as small 

 gray dots, and consist of a translucent, radiating filamentous 

 network. If kept for a few days at 37 C. they become 

 opaque and nodular, with radiating processes about the 

 periphery. Still later they develop a whitish downy ap- 



* " Virchow's Archives," cxv. 



28 



