PRODUCERS OF ABSCESS, CELLULITIS, ETC. 463 
along the line of puncture, followed by liquefaction of 
the medium, which rapidly extends to the sides of the 
test-tube. At the end of two days the yellow pigmen- 
tation begins to form, and this increases in intensity 
for eight days. Finally, the gelatin is completely 
liquefied, and the ‘‘ golden staphylococci” form a 
golden-yellow or orange-colored deposit at the bottom 
of the tube. Under unfavorable conditions the staphyl- 
ococcus aureus gradually loses its ability to make pig- 
ment and to liquefy gelatin. 
Growth on Agar. In streak and stick cultures on 
agar a whitish growth is at first produced, and this 
at the end of a few days becomes golden-yellow on the 
surface. The yellow pigmentation is produced only in 
the presence of oxygen; colonies found at the bottom 
of a stab culture or under a layer of oil remain white. 
Milk inoculated with this micrococcus at the end of 
from one to eight days is coagulated; bouillon and 
peptone solutions are densely clouded by the lux- 
uriant growth produced. 
In the three last-named culture media, as the result 
of the growth of the staphylococcus aureus, there is a 
production of acid in considerable quantities, these con- 
sisting chiefly of lactic, butyric, and valerianic acids. 
These acids have been supposed to play a part in the 
production of pus, in which, according to some ob- 
servers, they are often present. 
The staphylococcus is distinguished from most other 
pathogenic bacteria by its comparatively greater power 
of resistance to outside influences, desiccation, etc., as 
well as to chemical disinfectants. Cultures of the 
staphylococcus pyogenes in gelatin or agar retain their 
vitality for a year or more. Its thermal death-point is 
