294 MANUAL OF BACTERIOLOGY. 



possible to produce ulcerative endocarditis experimentally in 

 animals by the injection of the Staphylococcus pyogenes aureus 

 when the valves of the heart have first been mechanically in- 

 jured. The Staphylococcus pyogenes aureus has also been 

 found in acute abscesses of the lymph-nodes, tonsils, parotid 

 gland and mammary gland, in suppurating joint affections 

 and empyema. It appears, furthermore, in acute inflam- 

 mation of the serous membranes — pleuritis, pericarditis, 

 peritonitis — although less frequently than the Streptococcus 

 pyogenes. 



Staphylococcus Pyogenes Albus. — In form and manner 

 of growth this organism behaves like the Staphylococcus py- 

 ogenes aureus, with the exception that it produces no colored 

 growths and its cultures appear white. Its pathogenic prop- 

 erties are less marked, and it is a less frequent cause of sup- 

 puration than the Staphylococcus pyogenes aureus. It has, 

 however, been found in acute abscesses on numerous occasions. 



Staphylococcus Epidermidis Albus. — According to Welch, 

 the epidermis of man contains with great regularity the organ- 

 ism to which he gave the above name, and which he considers 

 to be a variety of Staphylococcus pyogenes albus. It grows 

 on all ordinary media, it liquefies gelatin, and coagulates milk 

 more slowly than the ordinary Staphylococcus pyogenes albus. 

 It is, furthermore, possessed of less marked pus-producing 

 tendencies. Welch found it impossible to sterilize the skin 

 so as to remove this micrococcus from it. The organism is 

 usually innocuous. It has been found in healthy wounds on 

 numerous occasions. It is capable of causing trouble in 

 wounds when necrotic or strangulated tissues are present, or 

 where a foreign body like a drainage-tube has been left in the 

 wound. It is a common cause of stitch abscesses. 



Streptococcus Pyogenes.— Appears as micrococci ar- 

 ranged in chains, usually in pairs, when the adjacent cocci 

 may be flattened. Sometimes the chains are very long. The 



