254 



SPIRILLUM CHOLERA ASIATICS. 



deeper into the medium as liquefaction progresses, and at last 

 turns a very peculiar pink. 



The gelatin stab culture is also quite characteristic. The 

 growth first takes place along the entire needle-track, being 

 more profuse on and near the surface, where the supply of 

 oxygen is greater. The liquefaction of the gelatin keeps pace 

 with the growth, beginning at the top as a small funnel-shaped 



FIG. 110. 



A characteristic series of cholera cultures in gelatin: one, two, three, four, and 

 six days' growth. (Dunham.) 



depression. This funnel or inverted cone gradually increases 

 in size until all the gelatin is liquefied. The culture slowly 

 settles to the bottom of the funnel, the end of which usually 

 shows a slight bulbous enlargement (Figs. 105, 110, and 

 111). The liquefied gelatin evaporates slowly, so that the fun- 

 nel is empty at the top. It looks as though it contained an 

 enormous air bubble. At the end of four or five weeks lique- 

 faction of the gelatin is complete. According to different 



