1 g6 BACTERIOLOGY. 



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 

 transparent, 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 

 layers or terraces. The growth is so slow that 



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

 Krankheiten des Menschen . 1884. 



