STAPHYLOCOCCUS PYOGENES AUREUS. 237 



In milk it rapidly brings about coagulation with acid 

 reaction. 



It is not motile, and being of the family of micro- 

 cocci, does not form endogenous spores. It possesses, 

 however, a marked resistance toward detrimental agen- 

 cies. 



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 staphylo- 

 COCGUS pyogenes aureus, and is the organism most fre- 

 quently concerned in the production of acute, circum- 

 scribed, suppurative inflammations. It is almost every- 

 where present, and is the organism that causes the sur- 

 geon so much annoyance. 



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 lower animals. 

 Its subcutaneous introduction into their tissues does not 

 always result in abscess-formation, and when it does, 

 there seems to have been some coincident interference 

 with the circulation and nutrition of these tissues which 

 renders them less able to resist its inroads. When in- 

 troduced into the great serous cavities of the lower 

 animals its presence here, too, 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 

 intestines, large quantities of bouillon cultures or watery 

 suspensions of this organism may, and repeatedly have 

 been introduced into the peritoneum without the slight- 



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