SAECIN^ IN THE AIR 109 



becomes clear. Agar cultures also show a fine golden- 

 yellow glossy coat. The sarcina grows slowly on potato. 

 Gelatine is but little liquefied. Sulphuric acid turns the 

 golden-yellow pigment bluish-green, and caustic potash, 

 red. 



Sarcina rosea. — This micro-organism, which was dis- 

 covered by Schroter, grows very rapidly on gelatine, slowly 

 on agar, forming minute cartilaginoid clumps ; while a 

 vigorous, intensely red deposit forms on potato. Multi- 

 plication takes place in broth with extraordinary rapidity, 

 and with development of a red sediment. Gelatine is very 

 speedily liquefied. The red pigment exhibits the same 

 chemical reactions as the colouring matter of Sarcina 

 aurantiaca. 



Sarcina lutea. — The sarcina of this name, described by 

 Schroter, grows very slowly on the gelatine plate, forming 

 small round colonies. A scanty coating appears diffused 

 over the surface, and advances into the deeper parts over 

 a narrow area in the form of yellow granules. A thickish 

 deposit of a fine yellow colour appears upon agar. Cultures 

 on potato are sulphur-yellow, and confined to the place of 

 inoculation. Gelatine is sometimes liquefied slowly. 



Staphylococci. — The Staphylococcus pyogenes was fully 

 described by Eosenbach, by Ogston, and by Passet. Its 

 distinctive characteristic is its power of causing suppuration, 

 and it may consequently be described as a specific pus- 

 coccus, being constantly found in suppurative' processes. 

 There are distinguished, according to colour, a Staphylo- 

 coccus pyogenes aureus, a Staphylococcus pyogenes albus, and a 

 Stapylococcus pyogenes citreus. It is but seldom in the 

 analysis of air that a plate culture destitute of staphylo- 

 cocci is obtained. 



According to E. Ullmann, these micro-organisms are 

 found in considerably greater numbers in the air of rooms 



