A CTINOM YCOSIS. 359 



contain the actinomyces granules, secured so as to be as 

 free from other micro-organisms as possible, is crushed 

 between glass plates or in a mortar, and then transferred 

 to plates or tubes as desired. The colonies make their 

 appearance as small gray dots, which consist of a trans- 

 lucent, radiating network of filaments. If kept at the 

 temperature of incubation for a few days, they become 

 opaque nodules with radiating processes about the periph- 

 ery. The growth occurs best in free access of oxygen, 

 though the organism is a facultative anaerobe. 



Upon blood-serum the nodular growths present a yel- 

 lowish or sometimes brick or rust-red color, and may sur- 

 round themselves with a whitish down of fine threads. 

 The colonies cling closely to the culture-media and are 

 firm, so that they are crushed with difficulty. If the sur- 

 face is scraped, spores and fine threads are secured. If 

 the mass is crushed, the branched filaments of the strep- 

 tothrix may be secured. The colonies become confluent 

 as time goes on, and a thick wrinkled membrane is 

 produced. The growth liquefies the blood-serum. 



In gelatin puncture cultures an arborescent growth is 

 produced and the gelatin liquefies. 



Upon agar-agar and glycerin agar-agar the picture is 

 similar to that of the blood-serum growth, but has less 

 and sometimes only a grayish color. The agar-agar 

 turns brown as the culture ages. 



In bouillon the growth takes the form of large granules 

 if allowed to stand quietly; of numerous small granules 

 if frequently shaken up. The granules are similar in 

 structure to those formed upon the dense media. The 

 bouillon does not become clouded. 



Upon potato the growth much resembles that upon 

 blood-serum, but is slower. The color is reddish-yellow 

 and the white down early makes its appearance. 



The growth also takes place in eggs, when long 

 branched filaments are observed. 



When the actinomyces are grown upon artificial media 

 their virulence is retained for a considerable length of 



