STREPTOCOCCUS PYOGENES. 479 
with granular edges or made up of granules. These 
granules may be very fine or fairly coarse. They are 
nearly translucent, with a whitish, yellowish, or brown- 
ish tinge. With characteristic cultures the gelatin is 
not liquefied, though occasionally, with unusual varie- 
ties, a certain amount of liquefaction has been observed 
to take place. 
Growth on Agar. On agar plates the colonies are 
visible after twelve to thirty hours’ growth, and present 
a beautiful appearance when magnified sufficiently to 
see the individual cocci in the chain. The colonies 
from different sources vary in size, thickness, mottling, 
color, and in the appearance of their borders. The 
streptococcus growing in short chains in bouillon shows 
but little tendency to form true loops, but rather pro- 
jecting rows at the edges of the colonies, while those 
growing in Jong chains show beautiful loops, which are 
characteristic of this organism. The colonies are nearly 
circular in shape when thinly scattered over the plates, 
but irregular in form when crowded together. 
Growth in Bouillon. Streptococci grow readily in 
slightly alkaline bouillon at 37° C., reaching their 
full development within thirty-six to forty-eight hours. 
Those which grow in long chains usually give an abun- 
dant flocculent deposit and leave the liquid clear. The 
deposit may be in grains, in tiny flocculi, in larger 
flakes, or in tough, almost membranous masses, the 
differences depending on the strength of union between 
the pairs of cocci in the chains. Some of the strepto- 
cocci growing in long chains, however, cause the broth 
to become cloudy. This cloudiness may be only tem- 
porary or it may be lasting. Those growing in short 
chains, as a rule, cloud the broth; this cloudiness 
