SPIRILLUM CHOLERA 81 



Plate cultures show signs of growth when kept at 

 21C. in the first 24 hours, and considerable growth 

 takes place in 48 hours. When the colonies are 

 numerous the whole plate assumes a ground-glass 

 appearance. The individual colonies are irregularly 

 spherical, rather sharply defined, granular, clear, 

 and highly refractile. Their appearance is well 

 expressed by Koch's comparison which likens them 

 to little heaps of pounded glass (Fig. 81). 



At a little later stage the granular character and 

 refractility increases, the outlines become more 

 circular, and the edge appears very finely festooned. 

 The surface of the colony is marked in such a 

 way that it appears to repeat the festooning of 

 the edge in concentric and diminishing circles. 

 With commencing liquefaction the colony becomes 

 surrounded by a sharp circle of fluid gelatine and the 

 colony sinks to the bottom of the funnel-shaped 

 hollow and appears sharply defined against the 

 refractile zone of liquefied gelatine, while it loses its 

 characteristic appearance. 



The comma bacillus is found in large numbers in 

 the intestinal contents in cases of cholera and 

 occasionally penetrates the lumen of the glands and 

 is found between the epithelium and basement 

 membrane ; this is scarcely to be wondered at con- 



