Tin: (;ROUP OF M.\u<;\A\r <KDI-:M.\ BAC/U.I 379 



poses the secretions, with the production of a putrefactive odor. On 

 the whole, considering the very wide distribution of this organi>ni in 

 nature, it is remarkable how few diseases are produced by it 



The Group of Malignant (Edema Bacilli. 



This group is widely distributed, being found in the superficial layers 

 of the soil, in putrefying substances, in foul water, and by invasion 

 from the intestine, in the blood of animals which have been suffocated. 

 One such organism was discovered (1877) by Pasteur in animals 

 after injections of putrefying liquids, and named by him "vibrion 

 septique." He recognized its anaerobic nature, but did not obtain 

 it in pure culture. Koch and Gaffky (1881) carefully studied this 

 micro-organism, described it in detail, and gave it the name "bacillus 

 oedematis maligni" (Fig. 115). This bacillus belongs to a group 

 which have lateral flagellae, produce oval spores, 

 and grow only anaerobically. FIG. 115 



Morphology. The oedema bacillus is a rod of S 



from 0.8, to l/^ in width, and of very varying * 



length, from 2, to 10/^ or more, according to the 



conditions of its cultivation and growth. It s / f 



usually found in pairs, joined end to end, but \ / 



may occur in chains or long filaments. It forms 



spores, and these are situated in or near the Bacillus of malignant oedema. 



middle of the body of the rods. Exceptionally 



the spores are near the ends. The spores vary in length and are oval 



in form, being often of greater diameter than the bacilli, to which they 



give a more or less oval or spindle shape. 



The bacilli s/am readily by the usual aniline colors employed, but 

 are decolorized by Gram's method. 



Biology. A strictly anaerobic, liquefying, motile bacillus. Forms 

 spores. It grows in all the usual culture media in the absence of oxygen. 

 Development takes place at 20 C., but more rapidly and abundantly 

 at 37 C. 



GROWTH IN GELATIN. This bacillus may be cultivated in ordinary 

 nutrient gelatin, but the growth is more abundant in glucose gelatin 

 containing 1 or 2 per cent, of glucose. After two to three days small, 

 almost transparent, circular colonies appear J to 1 mm. in diameter. 

 Later, as liquefaction increases, the colonies become grayish and then 

 confluent. Gas bubbles are formed and the gelatin liquefies. 



GROWTH ON AGAR. On agar plates the colonies appear as dull, 

 whitish points, irregular in outline, and when examined under a low- 

 power lens are seen to be composed of a dense network of interlacing 

 threads, radiating irregularly from the centre toward the periphery 



Blood serum is rapidly liquefied, with the production of gas. Cultures 

 of the malignant oedema bacillus give off a peculiar, diagreealde odor. 



Pathogenesis. The bacillus of malignant o-dema is especially patho- 

 genic for mice, guinea-pigs, and rabbits, although man, horses, dogs, 



