Cultivation 



not yet reached the surface of the gelatin soon show a 

 pale yellow color and an irregular contour. They are 

 coarsely granular, the largest granules being in the center. 

 As the colony increases in size the granules do the same 

 and attain a peculiar transparent character suggestive of 

 powdered glass. The slow liquefaction causes the colony to 

 be surrounded by a transparent halo. As the liquefied 

 gelatin evaporates, the colony begins to sink, and also to 

 take on a peculiar rosy color. 



Gelatin. In puncture cultures in gelatin the growth is 



Fig. 150. Spirillum cholerse asiaticae; gelatin puncture cultures aged 

 forty-eight and sixty hours (Shakespeare). 



again quite characteristic (Fig. 150). It occurs along 

 the entire puncture, best at the surface, where it is in 

 contact with the atmosphere. Liquefaction of the medium 

 begins almost at once, keeps pace with the growth, but 

 is always more marked at the surface than lower down. 

 The result of this is the formation 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 the growth appears to be surmounted by an air-bubble. 

 The luxuriant development of the spirilla in the liquefying 



