78 THE BACTERIA IN ASIATIC CHOLERA. [CH. IV.] 



whitish precipitate at the deep end, but also at the sides of 

 the liquefied gelatine there are present small granules easily 

 recognised under a lens, while the bulk of the liquefied 

 gelatine is translucent and almost clear. On the surface the 

 funnel-shaped depression occluded by an air-bubble is still 

 noticeable, but gradually diminishes and disappears as the 

 growth extends more and more laterally. The growth at 

 the end of three to five weeks has almost entirely liquefied 

 the gelatine through the whole depth of the original channel 

 of inoculation, and now the liquefaction proceeds deeper 

 and gradually invades the deepest parts of the gelatine, the 

 lower boundary of liquefaction being always marked by a 

 voluminous whitish precipitate. While the bulk of the 

 liquefied portion is tolerably clear there is present in most 

 tubes on the surface a kind of loose whitish film ; indeed I 

 have seen very few tubes in which the surface remained free 

 from it. Under the microscope the film is composed of 

 granular debris, and moving spirilla more or less matted 

 together. The above-mentioned funnel-shaped depression 

 of the gelatine, and the occlusion of it by an air-bubble 

 during the first week or two, are however not invariably 

 present ; they are not present if the nutritive gelatine is 

 weaker than TO per cent, gelatine; in 2 to 7 per cent, 

 gelatine the funnel-shaped depression and the occluding air- 

 bubble is wanting, the liquefaction proceeding rapidly, and 

 the surface end is from the outset marked by a drop of 

 liquefied gelatine. The progress of the growth is consider- 

 ably greater in such gelatine than in 10 per cent, gelatine. 

 On inoculating from the same culture of the comma-bacilli 

 two sets of tubes, one containing 5 per cent, the other 10 

 per cent, nutritive gelatine, and keeping them then under 

 precisely the same conditions at 20 C., a marked difference 

 will be found on inspecting the tubes after three to five days. 



