362 



INFECTIVE DISEASES. 



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

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

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

 characteristics. They appear as little masses, granular, and 



r^f 





<f>*. 





» <A 



ir7 



Fig. 147. — Flagella of Comma-bacilli ; stained by Lofflek's Method 

 (Fkankel and Pfeiffee). 



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

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

 of the resulting excavations. 



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







/'■■ 





Fig. 148.— Involution Forms, x 700 

 (Van Ermengem). 



Fig. 149.— Colonies of 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 needle track 



