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 long 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 G., 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 



