CULTURE OF THE CHOLERA SPIRILLUM. 317 



extends downward rather than laterally, and the colony 

 ultimately assumes the appearance of a dense, white 

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

 containing 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. 62. 



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. V. 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 

 not perfectly round. (See a, Fig. 62.) As growth 

 progresses, this homogeneous granular appearance is 

 replaced by an irregular lobulation, and ultimately the 

 sharply-cut margin of the colony becomes dentated or 



