198 MICROBIOLOGY 



and it is considered of much importance as a secondary in- 

 vader in cases of pulmonary tuberculosis. 



Morphology. This streptococcus grows in quite long 

 chains in bouillon. The individual segments are from 0.5 to 

 1.0 fji in diameter. 1 In smear preparations of pus they often 

 appear in short chains. Considerable variation in size is re- 

 corded. 



Staining. It stains readily with the usual aniline dyes. 

 It is positive to the Gram stain. 



Cultivation. It grows readily in the ordinary alkaline 

 media, especially bouillon and on agar. 



Agar. On this medium the colonies present a central 

 convex nuclear growth surrounded by a zone of thin almost 

 iridescent growth. The colonies are small, rarely attaining the 

 diameter of a pin head. There are, however, quite marked 

 differences exhibited by different cultures. The growth occa- 

 sionally develops a distinct yellowish tint in a few days. The 

 different varieties show variations in the color of the growth on 

 solid media. In the writer's experience the colonies are usually 

 of a greyish white color. 



Gelatin. In gelatin the growth is confined to the needle 

 tract. It is not vigorous and does not liquefy the medium. 



Blood serum. On this medium it develops tiny grayish 

 colonies. 



Bouillon. In alkaline bouillon it may impart a uniform 

 cloudiness or it may grow in flocculi which settle to the bottom 

 or sides of the tube. As a rule the long chained streptococci 

 grow in flocculent masses. A little ascitic fluid added to the 

 bouillon causes a more abundant growth. It ferments dex- 

 trose, lactose and saccharose in bouillon, producing acid but 

 no gas. 



Milk. Milk is often coagulated after a few days. 



Life conditions and properties. This streptococcus is 

 aerobic and facultative anaerobic. It is sensitive to changes 



1 Lehmann and Neumann. Atlas and Principles of Bacteriology, 

 1901. 



