Pathogenesis 347 



3. Organisms that produce acid and gas from inuHn but not from 

 glycerin. Form spores in glycerin but not in inuhn broth. Hem- 

 olysis and pathogenicity variable. 



4. Organisms that do not produce acid or gas from either 

 inulin or glycerin and from spores in both inulin and glycerin 

 broths. 



Pathogenesis. — The pathogenic powers of the bacillus are limited; 

 and while in some infected cases it seems to be the cause of death, 

 its power to do mischief in the body seems to depend entirely upon 

 the pre-existence of depressing and devitalizing conditions predis- 

 posing to its growth. 



Being anaerobic, the bacilli are unable to live in the circulating 

 blood, though they grow in old clots and in cavities, such as the 

 uterus, etc., where little oxygen enters, and from which they enter 

 the blood and are distributed. 



In support of these views Welch and Nuttall show that when 2.5 

 cc. of a fresh sugar-bouillon culture are injected into the ear-vein of 

 a healty rabbit, it usually recovers. After similar injection with 

 but I cc. of the culture, a pregnant rabbit carrying two dead embryos, 

 died in twenty-one hours. It seems that the bacilli were first able 

 to secure a foothold in the dead embryos, and there multiplied suffi- 

 ciently to bring about the subsequent death of the mother. 



After death, when the blood is no longer oxygenated, the bacilli 

 grow rapidly, with marked gas-production, which in some cases is 

 said to cause the body to swell to twice its natural size. The effect 

 upon guinea-pigs does not differ from that upon rabbits, though 

 gaseous phlegmons are sometimes produced. 



Pigeons, when subcutaneously inoculated in the pectoral region, 

 frequently die in from seven to twenty-four hours, but may recover. 

 Gas-production causes the tissues to become emphysematous. 



Intraperitoneal inoculation sometimes causes fatal purulent peri- 

 tonitis of laboratory animals. 



. Sources of Infection. — The infection seen in man usually occurs 

 from wounds into which earth has been ground, as in the case of a 

 compound, comminuted fracture of the humerus, with fatal infec- 

 tion, reported by Dunham, or in wounds and injuries in the neigh- 

 borhood of the perineum. 



Among the twenty- three cases reported by Welch and Flexner* 

 we find wounds of the knee, leg, hip, and forearm, ulcer of the 

 stomach, typhoid ulcerations of the intestine, strangulated hernia 

 with operation, gastric and duodenal ulcer, perineal section, and 

 aneurysm as conditions in which external or gastro-intestinal in- 

 fection occurred. 



Dobbin, t P. Ernst, J Graham, Stewart and Baldwin, § and Kronig 



* "Journal of Experimental Medicine,'" Jan., 1896, vol. i, No i. 

 t " Bull. Johns Hopkins Hospital," Feb., 1897, No. 71, p. 24. 

 t "Virchow's Archiv.," Bd. cxxxm, Heft 2. 

 § "Columbus "Med. Jour.," Aug., 1893. 



