364 THE MUCOSUS CAPSULATUS GROUP 



prolonged cultivation in the usual artificial laboratory media. Ordi- 

 nary anilin dyes color the organisms readily, and they are Gram- 

 negative. 



Isolation and Culture. The members of the Mucosus Capsulatus 

 Group grow readily on artificial media. The colonies on agar are white 

 or gray, from 1.5 to 3 mm. in diameter, very viscid, and raised; they 

 tend to become confluent. When touched with a platinum needle 

 the growth may be drawn away as a tenacious, sticky filament. In 

 gelatin, a non-characteristic filamentous growth occurs along the line 

 of inoculation and the surface becomes covered with a white, glisten- 

 ing raised colony. The gelatin is not liquefied. Milk is acidified, and 



FIG. 51. Bacillus mucosus capsulatus. X 1000. 



frequently the accumulation of acid leads to coagulation. A light- 

 pink color is imparted to litmus milk and coagulation is irregular in 

 this medium. Broth is clouded, and a slimy, viscid sediment collects 

 at the bottom of the tube. A majority of strains produce gas bubbles 

 on potato. 



The organisms are aerobic, facultatively anaerobic. Growth takes 

 place at 8 to 10 C., but 37 C. is the optimum temperature. Little 

 or no growth occurs above 43 C. 



Products of Growth. The majority of strains do not form indol, 

 but occasional cultures give a marked reaction for this substance. 1 

 Practically all strains form a mucinous substance on artificial media. 



The reactions of fermentation have been used as a basis for separa- 

 tion into types by Perkins, 2 who groups the organisms in the following 

 manner : 



1 Kendall, Day and Walker, Jour. Am. Chem. Soc., 1913, xxxv, 1237. 



2 Jour. Infec. Dis., 1904, i, 241. 



