CHOLERA. 317 In size, and attain a peculiar transparent character which is suggestive of powdered glass. The commencement of liquefaction causes the colony to be surrounded with a transparent halo. When this occurs the colony begins to sink, from the digestion and evaporation of the medium, and also to take on a peculiar rosy color. In puncture-cultures in gelatin the growth is again so characteristic that it is quite diagnostic (Fig. 83). The 110.83.—Spirillum cholera Asiatica; gelatin puncture-cultures aged forty- eight and sixty hours (Shakespeare). growth takes place along the entire puncture, but devel- ops best at the surface, where it is in contact with the atmosphere. An almost immediate liquefaction of the medium begins, and, keeping pace with the rapidity of the growth, is more marked at the surface than lower down. The result of this is the occurrence of a short, rather wide funnel at the top of the puncture. As the growth continues evaporation of the medium takes place slowly, so that the liquefied gelatin is lower than the solid surrounding portions, and appears to be surmounted by an air-bubble.