244 MANUAL OF BACTERIOLOGY. 



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 frequeiitly than the Streptococcus 

 pyogenes. 



Staphylococcus pyogenes albus. — In form and manner 

 of growth this organism behaves like the Staphylococcus 

 pyogenes aureus, with the exception that it produces no col- 

 ored growths and its cultures appear white. Its pathogenic 

 properties are less marked, and it is a less frequent cause of 

 suppuration 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, 

 hquefies 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 arranged 

 in chains, usually in pairs, when the adjacent cocci may be 

 flattened. Sometimes the chains are very long. The diameters 

 of the cocci vary from 0.4 to i /-!. Attempts have been made 

 to create varieties of streptococci according to the length of the 

 chains. On that basis a Streptococcus brevis and a Strepto- 

 coccus longus have been described. 



