116 CLINICAL BACTERIOLOGY. 



is -\-6 C. (42.8 F.), the temperature -maximum +44 C. 

 (i 1 1.2 F.), the temperature-optimum from +34 C. (93.2 

 F.) to +38 C. (100.4 F-) : thus > the temperature of the 

 body. On gelatin-plates, with low powers of the micro- 

 scope, they form at first round, coarsely granular colonies, 

 with sharply limited borders, and of whitish-gray color ; 

 later, they become orange -yellow, and liquefy the gelatin 

 with moderate rapidity. In gelatin stab-cultures develop- 

 ment takes place along the line of inoculation, with liquefac- 

 tion. On agar streak-cultures there forms a moist, shining, 

 golden-yellow raised column, and also upon potatoes. 

 Bouillon is rendered densely turbid, and presents a yellow 

 sediment. Milk is coagulated. In milk and bouillon, prin- 

 cipally lactic acid, also propionic acid, valerianic acid, and 



w 



^ _ 



Fig- 37. Staphylococcus pyogenes aureus, from an agar-agar culture (Giinther). 



isobutyric acid, are formed. Facultative anaerobic, the 

 Staphylococcus aureus generates its yellow pigment only in 

 the presence of oxygen. Cultures retain their vitality for 

 more than a year. They are destroyed by brief exposure 

 to the action of live steam, and in pus dried on silk threads 

 by exposure to the action of two or three per cent, carbolic 

 acid for five minutes. 



Staphylococcus pyogenes albus (Fig. 38) is absolutely 

 identical with the foregoing except that it does not give 

 rise to pigment-formation. 



Staphylococcus pyogenes citreus generates a citron- 

 yellow ferment, but in its other properties it is identical 

 with the Staphylococcus aureus. 



