QUARTER- EVIL. 



401 



name "blackleg" by which the disease is sometimes known. The 

 bacillus which produces this condition is present in large numbers in 

 the affected tissues, associated with other organisms, and also occurs 

 in small numbers in the blood of internal organs. 



The bacillus morphologically closely resembles that of malignant 

 oedema. Like the latter, also, it is a strict ancerobe, and its conditions 

 of growth as regards tem- 

 perature are also similar. 

 It is, however, somewhat 

 thicker, and does not 

 usually form such long 

 filaments. Moreover the 

 spores, which are of oval 

 shape and broader than 

 the bacillus, are almost 

 invariably situated close to 

 one extremity, though not 

 actually terminal (Fig. 

 103). The characters of 

 the cultures, also, resemble 

 those of the bacillus of 

 malignant cedema, but in 

 a stab culture in glucose 

 agar there are more 

 numerous and longer FIG. 103. Bacillus of quarter-evil, show- 

 lateral off-shoots, the ing spores. From a culture in glucose agar, 

 growth being also more incubated for three days at 37 C. 

 luxuriant (Fig. 102, c). Stained with weak carbol-fuchsin. x 1000. 

 This bacillus is actively 

 motile, and possesses numerous lateral flagella. 



The disease can be readily produced in various animals, e.g. 

 guinea - pigs, by inoculation with the affected tissues of diseased 

 animals, and also by means of pure cultures, though a considerable 

 amount of the latter is usually necessary. The condition produced in 

 this way closely resembles that in malignant cedema, though there is 

 said to be more formation of gas in the tissues. Rabbits are practically 

 immune against this disease, whilst they are comparatively susceptible 

 to malignant cedema. 



The disease is one against which immunity can be readily produced 

 in various ways, and methods of preventive inoculation have been 

 adopted in the case of animals liable to suffer from it. This subject was 

 specially worked out by Arloing, Cornevin, and Thomas, and later by 

 others. Immunity may be produced by injection with a non-fatal 

 dose of the virus, or by injection with larger quantities of the virus 

 attenuated by heat, drying, etc. It can be produced also by the pro- 

 ducts of the bacilli obtained by filtration of cultures. 



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