SUPPURATION. 219 



does not produce fermentation with gas-production. It 

 belongs to the group of facultative aerobes. 



In milk it rapidly brings about coagulation \vith acid 

 reaction. 



It is not motile, and being of the family of micrococci, 

 does not form endogenous spores. It possesses, however, 

 a marked resistance toward detrimental agencies. 



In bouillon it causes a diffuse clouding, and after a 

 time presents a yellow sedimentation. 



This organism is the commonest of the pathogenic 

 bacteria with which we shall meet. It is the staphy- 

 lococcus pyogenes aureus, and is the organism most 

 frequently concerned in the production of acute, cir- 

 cumscribed, suppurative inflammations. It is almost 

 everywhere present, and is the organism most dreaded 

 by the surgeon. 



In studying its effects upon lower animals a number 

 of points are to be remembered. While it is the etio- 

 logical factor in the production of most of the suppura- 

 tive processes in man, still it is with no little difficulty 

 that these conditions can be reproduced in the lower 

 animals. Its subcutaneous introduction into their tis- 

 sues does not always result in abscess- formation, and 

 when it does there seems to have been some coincident 

 interference with the circulation in these tissues which 

 render them less able to resist its inroads. When 

 introduced into the great serous cavities of the lower 

 animals it is not always followed by the production 

 of inflammation. If the abdominal cavity of a dog, for 

 example, be carefully opened so as to make as slight a 

 wound as possible, and no injury be done to the intes- 

 tines, large quantities of bouillon cultures or watery 

 suspensions of this organism may, and repeatedly have 



