478 BACTERIOLOGY. 
quently exceed their fellows greatly in size, especially 
in old cultures, when this may be considered to be the 
result of involution forms. (See Figs. 61, 62, 63, and 
64.) 
They siain readily by aniline colors and by Gram’s: 
method. 
Streptococci from solidified serum cul- Streptococcus growing in long 
ture appearing mostly as diplococci. chains in bouillon culture. < 1000 
X 1000 diameters. diameters, 
Biological Characters. Streptococci grow readily in 
various liquid and solid culture media. The most 
favorable temperature for their development is from 
30° to 87° C., but they multiply freely at ordinary 
room-temperature—18° to 20° C. They are faculta- 
tive anaérobes, growing both in the presence and ab- 
sence of oxygen. 
Growth on Gelatin. Tubes of gelatin which have 
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, 
