564 THE BACILLUS OF MALIGNANT (EDEMA 



Spores are rapidly formed in the bodies of dead animals and in cultures. 

 The spore appears as a brilliant refractile oval point which causes a swelling 

 in the centre or towards the end, but very rarely exactly at the end of the 

 bacillus. 



There appear to be several varieties of the bacillus distinguished by differences 

 of motility, degrees of virulence and the rapidity with which they liquefy serum. 

 Great uncertainty, however, still exists on this point and it is reasonable to suppose 

 that the so-called different varieties are merely modified forms of one and the same 

 organism. 



Staining reactions. The bacillus of malignant oedema is easily stained 

 by the basic aniline dyes. It is gram-positive but the reaction is inconstant 



FIG. 265. The bacillus of malignant FIG. 266. The bacillus of malignant 

 oedema. Film from a 3 days' growth oedema. Flagella. x 1200. 



on agar. Dilute carbol-fuchsin. (Oc. 

 IV, obj. ^th, Reich.) 



unless certain precautions be observed. The best dye is carbol-gentian- 

 violet, and it should be left on the film for 5 minutes before being replaced 

 by the iodine solution. The bacillus stains well by Claudius' method. 

 Spores and flagella may be stained by the methods described in Chap. IX. 



2. Cultural characteristics. 



Conditions of growth. The bacillus of malignant oedema is a strict anaerobe 

 and can only be grown by the methods described in Chap. VI. 



The bacillus of malignant oedema is one of the least strictly anaerobic of all the 

 anaerobic organisms and grows quite well in media from which the air has been 

 only partially removed. Rosenthal has been able to adapt it to aerobic conditions. 



Growth does not take place below 15 C. The optimum temperature is 

 about 37 C. Very satisfactory cultures can be obtained by incubating at 

 41 C. (Besson). 



Culture media. Broth. A well marked cloudiness appears after incubating 

 at 37 C. for 12 or 20 hours. Indol and evil smelling gases (C0 , H, hydro- 

 carbons and volatile sulphur compounds) are produced in considerable 

 amount. The broth soon clears, the growth precipitating to the bottom of 

 the tube. As long as the broth is cloudy it contains numerous bacilli which 

 form spores after about 20-24 hours. In the deposit spores and granular 

 disintegrated bacilli only are to be found. 



Albuminous media. The culture is similar to that in broth but more 

 abundant. Broth containing blood or ascitic fluid, Martin's broth, serum 

 either pure or diluted with an equal volume of water or broth, and meat 

 juice sterilized by filtration through a Chamberland bougie all give very 

 abundant growths. 



The following medium appears to give the best cultivations (Besson). To 500 

 grams of finely minced lean meat add 500 c.c. of distilled water and a large pinch 



