TEXT-BOOK OF BACTERIOLOGY. 323 



oxygen, soon assume a beautiful golden-yellow coloring and can 

 thus be recognized at the first glance. 



In the test-tilbe the growth proceeds along the entire inocula- 

 tion puncture. The gelatin is generally entirely liquefied, most 

 rapidly in the superficial layers. The cocci slowly sink to the bot- 

 tom and gather there as a distinctly-yellow, crumbling sediment, 

 the upper portion of the gelatin appearing but slightly cloudy. A 

 strange, acidulous odor, like that of paste, may soon be noticed in 

 the culture. The Staphylococcus aureus develops most characteris- 

 tically on oblique agar-agar. There appears along the inoculation 

 line and restricted to its neighborhood, an orange-yellow, moist, 

 glistening film, looking as if the surface had been coated with oil- 

 paint. 



The pigment is particularly' beautiful when the cocci are culti- 

 vated outside the incubator. In the latter, the growth is so luxuri- 

 ant and rapid that the production of coloring matter is retarded 

 and the edges of the culture frequentlj' remain nearly white. 



The Staph, aureus thrives excellently on potatoes, and at a high 

 temperature a thick, juicy, yellow coat with the peculiar odor is 

 formed. 



Bouillon becomes evenly and thickly cloudy ; in sterile milk the 

 casein is precipitated and slowly peptonized. 



The fact that the Staphylococcus aureus is not a regular and 

 harmless concomitant of purulent inflammatory processes, but their 

 cause, has been demonstrated by successful transmissions. The 

 results corresponded to the natural conditions inasmuch as they 

 produced the most varying forms of suppuration, and thus explained 

 more fully the occurrence of this coccus under so many various 

 conditions. 



Inoculations on man were performed by Garre, Bockhart, Schim- 

 melbusch, Bumm, and others. Garre experimented on himself. 

 He once applied a pure culture of this coccus to small wounds on 

 the edge of a finger-nail and noticed a progressive suppuration 

 around it; at another time, he rubbed larger quantities of the coc- 

 cus on the sound skin of his forearm and caused by it the appear- 

 ance of a very large carbuncle which required weeks to heal and 

 left behind distinct scars. The aureus was again obtained from 

 the contents of the abscess. 



The other investigators reached similar results, while the re- 

 sults of experiments with animals were not so uniform. 



The mode of infection has a determining influence; the action 

 of the bacteria appearing under some circumstances in a very dif- 

 ferent light. Simple inoculation does not succeed with mice, Guinea- 



