380 CHOLERA. 



media, and with the exception of that on potato, growth 

 takes place at the ordinary room temperature. The most 

 suitable temperature, however, is that of the body, and 

 growth usually stops about 16 C., 

 though in some cases it has been 

 obtained at a lower temperature. 



Peptone gelatine. On this medium 

 the organism grows well and produces 

 liquefaction. In puncture cultivations 

 at 22 C. a whitish line appears along 

 the needle track, at the upper part of 

 which liquefaction commences, and as 

 evaporation quickly occurs, a small bell- 

 shaped depression forms, which gives 

 the appearance of an air-bubble. On 

 the fourth or fifth day we get the fol- 

 lowing appearance : there is at the 

 surface the bubble-shaped depression ; 

 below this there is a funnel-shaped area 

 of liquefaction, the fluid being only 

 slightly turbid, but covered on its surface 

 with a more or less complete pellicle, and 

 showing at its lower end thick masses of 

 growth of a more or less spiral shape 

 (Fig. 94). The liquefied portion grad- 

 ually tapers off downwards towards the 

 needle track. (This appearance is, how- 

 FIG. 94. Puncture ever, in some varieties not produced 

 culture of the cholera till much later, especially when the 



g P e!alT- in si/ e l ;s e S elatin is Ver T Stiff ' a " d > fn ther 

 growth. Natural size, varieties which liquefy very slowly, may 



not be met with at all.) At a later 

 stage, liquefaction spreads and may reach the side of the 

 tube. 



In gelatine plates the colonies are somewhat characteristic. 

 They appear as minute whitish points, visible in twenty-four 

 to forty -eight hours, which, under a low power of the 

 microscope, do not present a smooth circular outline, but 



