362 



INFECTIVE DISEASES. 



16° to 20° C, the colonies develop as little specks, which begin to 

 be visible after about twenty-four hours. Examined with a low 

 power, and a small diaphragm, these colonies have the following 

 characteristics. They appear as Uttle masses, granular, and 





v> 



%i 



IjJ^^^ 



Pig. 147.— Flagella op Comma-bacilli; stained byJ Lopflbe's MEi'Hon 

 (Peankel and Pfeifpee). 



yellowish- white in colour, and sometimes very faintlyi tinged with 

 red, which have liquefied the gelatine, and sunk down to the bottom 

 of the resulting excavations. 



In test-tubes of slightly alkaline nutrient gelatine (10 per cent.), 





J <■ 



Fig. 148. — Involution Forms, x 700 

 (Van Ekmbngbm). 



Fig. 149.— Colonies op Comma.bacilli 

 on Nutrient Gelatine, Natural 

 Size (Koch). 



the appearance of the growth is very striking. In typical cultures 

 it begins to be visible in about twenty-four hours. Liquefaction 

 sets in very slowly, commencing at the top of the jieedle track 



