P,Y"/;rr/;/Y.s o/-' ABSCESSES, CLLIA' I.ITIS AM) SEPTIC /-/W/.l 339 



temperature 18 to 20 C. Tlrey are facultative anaerobes, growing 

 both in the presence and absence of oxygen. 



Cultivation. GROWTH o\ (ii.i.niv. Tubes of gelatin which ha\v 

 been inoculated with streptococci by puncture with the platinum needle 

 show on the surface no growth beyond the point of entrance. In the 

 depth of the gelatin on the second or third day a distinct, tiny band 

 appears, 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 brownish tinge. With characteristic cultures the 

 gelatin is not liquefied, though occasionally, with saprophytic varieties, 

 a certain amount of liquefaction has been observed to take place. 



GROWTH ox AGAR. On agar plates the colonies are visible after 

 twelve to thirty hours' growth at 37 C., and present a beautiful appear- 

 ance when magnified sufficiently to see the individual cocci in the 

 chain. The colonies are small, not averaging over 0.5 mm. in diameter 

 (pin-head). From different sources they 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 projecting rows at the edges of the colonies, while 

 those growing in long chains show beautiful loops, which are character- 

 istic 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. Most streptococci grow well in slightly alka- 

 line bouillon at 37 C., reaching their full development within thirty-six 

 to forty-eight hours. Those which grow in long chains usually give 

 an abundant 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 streptococci 

 growing in long chains, however, cause the broth to become cloudy. 

 This cloudiness may be only temporary or it may be lasting. Those 

 growing in short chains, as a rule, cloud the broth, this cloudiness 

 remaining for days or weeks. A granular deposit appears at the 

 bottom of the tube. An addition of 0.5 to 1 per cent, glucose aids the 

 development of streptococci, but the acid produced tends later to hasten 

 their death and make them lose virulence. A trace of calcium aids 

 the growth. This is best added as a piece of marble, which has tin- 

 additional advantage of neutralizing some of the acids produced. 



GROWTH IN ASCITIC OR SERU.M BOUILLON. The development in this, 

 which is the test medium for the growth of the streptococcus, is more 

 abundant than in plain bouillon. The liquid is clouded, and a precipitate 

 only occurs after some days, the fluid gradually clearing. The addition 

 of blood serum frequently causes streptococci, growing in short chains 

 in nutrient bouillon, to produce long chains. The reverse is also true, 

 and in the blood all forms are usually found, partly, at least, as diplo- 

 cocci or in short chains. 



EFFECT ON IM LIN. This is not fermented by most varieties 



