334 



BACTERIOLOGY. 



hours as small, round, or oval, white or cream-white 

 points, and when located superficially there can be de- 

 tected around them a narrow transparent zone of lique- 

 faction. As growth continues, this liquefaction extends 

 downward rather than laterally, and the colony ulti- 

 mately assumes the appearance of a dense, white mass 

 lying at the bottom of a sharply-cut pit or funnel con- 

 taining transparent fluid. This liquefaction is never 

 very widespread nor rapid, and rarely extends for more 

 than one millimetre beyond the colony proper. On 

 plates containing few colonies there is but little or no 

 tendency for them to become confluent, and, as a rule, 

 they do not exceed 2 to 3 mm. as an average diameter. 



FIG. 66. 



c d 



Developmental stages of colonies of the spirillum of Asiatic cholera at 

 20 to 22 C. on gelatin. X about 75 diameters. 



a. After sixteen to eighteen hours. 6. After twenty-four to twenty-six 

 hours, c. After thirty-eight to forty hours, d. After forty-eight to fifty 

 hours, e. After sixty-four to seventy hours. 



When examined under a low magnifying lens the 

 very young colonies (sixteen to eighteen hours) appear 

 as pale, translucent, granular globules of a very delicate 

 greenish or yellowish- green color, sharply outlined and 



