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 little masses, granular, and 



FIG. 147. FLAGELLA OF COMMA-BACILLI ; STAINED BY LOFFLER'S METHOD 

 (FRANKEL AND PFEIFFER). 



yellowish-white in colour, and sometimes very faintly 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.), 



(X, 



FIG. 148. INVOLUTION FORMS, x 700 FIG. 149. COLONIES OF COMMA-BACILLI 

 (VAN ERMENGEM). 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 



