MICEOCOCCUS LANCEOLATUS. 501 



action of germicidal agents. Its pathogenic power also 

 undergoes attenuation very rapidly when cultivated on 

 artificial media. It is non-motile. 



In the cultivation of this organism one of the most 

 important considerations is the reaction of the media 

 employed. According to Fraenkel, Sternberg and 

 others, it grows only in culture media when they have 

 a slightly alkaline reaction. Kruse and Pansini showed 

 by their investigations that, according to the source 

 from which it was obtained, it grows at times equally 

 well in a slightly alkaline or slightly acid medium. 

 Not infrequently, however, all experimenters have 

 found that no growth at all occurs, irrespective of the 

 composition or reaction of the media employed. The 

 weight of opinion, nevertheless, seems to be in favor of 

 the selection of a slightly alkaline medium. 



The organism grows, as has been said, on all the cul- 

 ture media ordinarily employed for the cultivation of 

 bacteria viz., on agar and gelatin, in bouillon, ascitic 

 fluid, and blood-serum. The best medium for its 

 growth is a mixture of one-third ascitic or pleuritic 

 fluid and two-thirds bouillon. It grows readily in 

 milk, causing coagulation with the production of acid, 

 though this is not constant. 



Growth on Agar. Cultivated on plain nutrient agar, 

 after forty-eight hours in the incubator, there ap- 

 pears a thin, colorless layer composed of dilute non- 

 confluent colonies. If blood-serum or ascitic fluid be 

 added to the agar the individual colonies are larger and 

 closer together, and the growth is more distinct in con- 

 sequence and of a grayish color. The surface colonies 

 resemble those of some of the streptococci growing in 

 short chains; they are almost circular in shape, finely 



