SYSTEMATIC AND DESCRIPTIVE. 115 



and in chains ; occur in acute abscesses. Inocu- 

 lation of guinea-pigs or mice with pus containing 

 these cocci, or with a pure cultivation of the same, 

 causes suppuration at the site of injection, and 

 death with symptoms of blood-poisoning. In the 

 blood, in the tissue around the abscess, and in the 

 pus the cocci are found singly or in zoogloea or 

 chains. Their appearances in cultivation-media have 

 been very minutely described.* Cultivated in a 

 streak on the surface of nutrient gelatine on a glass 

 plate, they form at first whitish, somewhat trans- 

 parent, rounded spots, of the size of small grains 

 of sand. They develop but slightly on this 

 medium, even at the highest temperature attain- 

 able without liquefying the gelatine. On nutrient 

 agar-agar they grow most energetically at a 

 temperature of 35 37 C. On this medium also, 

 they show a tendency to form little spots, which 

 finally become about the size of a pin's head. 

 If a streak is made with a needle well charged 

 with a fresh cultivation, growth in a continuous line 

 is obtained, but still showing an inclination to form 

 centres. In its further development the middle 

 of the cultivation is heaped up, and presents a 

 pale brownish coloration, while the periphery is 

 flattened, except at the extreme margin, which is 

 again raised up, and often with a spotted appear- 

 ance. Still later, the periphery develops successive 



* Rosenbach, Mikro-organismen bei den Wund-Infections- 

 Krankheiten des Menschen. 1884. 



