GENUS STREPTOCOCCUS 201 



tative anaerobe. It grows in slightly acid, neutral or alkaline 

 media. The most favorable temperature is about 38 C. It 

 will not grow at 41 C. 



Agar. On agar the growth appears as small shiny gray- 

 ish colonies about 1.5 mm. in diameter. They consist of a 

 darker center surrounded by an irregular pale bluish zone. In 

 the depth of the agar the growth appears as grayish white 

 colonies with slightly fimbriated borders. The growth is more 

 vigorous on glycerine-agar and serum-gelatin- agar. 



Gelatin. On gelatin, the growth is not noticeable until 

 the fourth or fifth day, when minute grayish white colonies are 

 observed. These colonies are never larger than a pin head and 

 have a fimbriated border. The gelatin is not liquefied. 



Potato. It does not grow on potato. 



Bouillon. In alkaline bouillon, growth appears in 24 

 hours, in the form of long chains which appear as fine flocculi 

 in the liquid at the bottom and along the sides of the tube, 

 leaving the medium clear. After the growth settles, the sedi- 

 ment is not viscid, and upon shaking breaks up into small 

 masses. Some cultures impart a more uniform cloudiness to 

 the medium. In dextrose bouillon, the growth is more vigorous 

 than in simple peptonized bouillon and the reaction becomes 

 acid. A similar reaction takes place in saccharose and lactose 

 bouillon. 



Milk. It produces no visible change in milk. In litmus 

 milk the blue coloration changes to a pale pink in the course 

 of a few days. In the writer's experience coagulation has not 

 taken place. 



Life conditions and properties. It is aerobic and facul- 

 tative anaerobic. It does not produce indol. Toxins have not 

 been described. 



Resistance. It is destroyed at 60 C. in 15 minutes. 

 Mohler found it would not develop after 11 minutes exposure 

 to that temperature. It is killed with weak solutions of car- 

 bolic acid (1%) and corrosive sublimate (1-2000) in from two 

 to three minutes. Creolin in a 1 per cent solution is destruc- 

 tive. 



