494 ANAEROBIC BACTERIA 



takes place readily, and the spores occur typically in the centre of 

 the rod, giving it a slightly swollen appearance. The organism stains 

 readily with ordinary anilin dyes and is usually regarded to be Gram- 

 negative, although some claim it is Gram-positive. 1 



Isolation and Culture. B. cedematis maligni is a strict anaerobe, 

 and the organisms are best obtained in pure culture from the edema- 

 tous lesions produced in rabbits or in guinea-pigs by inoculation of 

 them with garden soil. The organism grows readily under anaerobic 

 conditions on dextrose agar, and the colonies produced are very 

 filamentous. 



FIG. 69. Bacillus cedematis maligni, spore formation. X 1000. (Kolle and Hetsch.) 



The organism grown anaerobically on gelatin produces similar 

 colonies; the gelatin is liquefied in from three to five days. 2 The 

 colonies are rather small on this medium, exhibit radiating edges, and 

 are surrounded by a liquefied zone. 



Milk is both coagulated and peptonized, but no gas is formed in it. 



Blood serum is rapidly liquefied and it is an excellent medium for 

 the development of this organism. 



Artificial cultures possess an offensive odor. Broth (anaerobic) is 

 clouded by the organism after twelve to twenty-four hours' incubation, 

 but usually clears up after three to six days. The organisms grow 

 much better in albuminous media, particularly those containing blood 

 serum. 



Growth does not take place below 15 C. nor above 42 C. The 

 optimum temperature is 37 C. The organism is an obligate anaerobe 

 and sporulation only takes place anaerobically. 



1 Kutscher, Ztschr. f. Hyg., 1894, xviii, 339. Claudius, Ann. Inst. Past., 1897, 335. 



2 Liborius, Ztschr. f. Hyg., 1886, i, 159, 



