CHOLERA BACTERIA 



149 



slowly liquefied, a funnel-shaped cavity formed, holding the 

 colony in its narrow part, at the bottom, and on the fifth day 

 all the gelatin is liquid. If the colonies of three days' growth 

 are placed under microscope, they appear as if composed of 

 small bits of frosted glass with sharp, irregular points. 



Stab-culture. After thirty hours a growth can be distin- 

 guished along the needle-track, and on the surface a little 

 cavity is formed, filled by a bubble of air, and this liquefaction 



Fig. 65. Cholera colonies after thirty hours (Xioo) (Frankel and 



Pfeiffer). 



proceeds until, on the sixth day, it has reached the sides of 

 the tube, tapering, funnel-shaped, to the bottom of the tube. 

 After several weeks the spirilla are found in little collections 

 at the bottom of the fluid gelatin. In eight weeks the bacilli 

 have perished. 



Agar. Stroke cultures. A shiny white layer which lasts 

 many months. 



Alkaline Agar. Plates at 37 C. Flat discs, transparent, 

 grayish blue. 



