82 SUPPURATION. 



intense than those of the aureus. The cultures of both the yellow 

 and white staphylococcus upon gelatine present an irregular sur- 

 face, and the margins are dotted with numerous minute globular 

 projections. Both of these microbes liquefy gelatin, but agar- 

 agar and coagulated blood-serum are not similarly affected. The 

 cultures, especially if kept moist, retain their virulence for a very 

 long time. Rosenbach found a culture upon serum active after 

 the lapse of two years. 



3. STAPHYLOCOCCUS PYOGEXES CITREUS. Like the former, 

 liquefies gelatin. ' Cocci singly, or in pairs, or zoogloea. If cul- 

 tivated on nutrient gelatin, or agar-agar, a sulphur or lemon- 

 yellow growth develops after twenty-four hours, which, at that 

 time, resembles the aureus, but later does not change into an orange- 

 yellow color. In both, the development of pigment only takes 

 place where the colonies are in contact with the air. According to 

 Passet, its pathogenic properties are somewhat less than those of 

 the aureus and albus. This latter statement has received the con- 

 firmation of Cheyne. When inoculated under the skin of mice, 

 guinea-pigs, or rabbits, an abscess forms after a few days, from 

 which a fresh culture of the microbe can be obtained. 



4. STAPHYLOCOCCUS CEREUS ALBUS. Cocci also obtainable 

 from pus, but distinguished by forming on nutrient gelatin a 

 white, slightly shining layer, like drops of white wax, with some- 

 what thickened, irregular edge The needle puncture develops 

 into a grayish-white, granular thread. In plate cultivations, on 

 the first day, white points are observed, which spread themselves 

 out on the surface to spots of one-half a millimetre in diameter ; 

 when cultivated on blood-serum, a grayish-white, slightly shining 

 streak develops ; and on potato the cocci form a layer which is 

 similarly colored. This microbe is not pathogenic in rabbits. 



5. STAPHYLOCOCCUS CEREUS FLAVUS. If cultivated on gela- 

 tin, the growth, which is at first white, becomes a citron-yellow 

 color, somewhat darker than staphylococcus pyogenes citreus. Both 

 varieties of staphylococcus cereus are found in pus and cultures in 

 colonies. Inoculations in rabbits have proved harmless. 



6. STAPHYLOCOCCUS FLAVESCEXS. This organism was found 

 in an abscess by Babes, and occupies an intermediate position 

 between the staphylococcus aureus and albus. On gelatin, the 

 growth forms a colorless layer, and causes liquefaction. It is fatal 

 to mice, sometimes causing abscesses, and, in large doses, septi- 

 caemia. 



7. MICROCOCCUS PYOGENES TENUIS. Roseubach found this 

 microorganism in a large abscess which had given rise to no 

 general symptoms. It is of rare occurrence. On agar-agar it 

 forms an exceedingly delicate, almost invisible, white film. The 



