472 PATHOGENIC MICROORGANISMS 



later described by Frankel/ and named by him Bacillus phlegmonis 

 emphysematossB. 



Similar, probably identical, bacilli have been found and reported sub- 

 sequently by other observers, ignorant of the work of Welch and Nuttall. 

 Such are the B. perfringens (Veillon and Zuber), and B. emphysematis 

 vaginae (Lindenthal, Wien. khn. Woch., 1897), and others. 



Welch ^ first obtained the bacillus from the intravascular blood of a 

 case of ruptured aortic aneurysm, autopsied six hours after death, his 

 attention being called to the blood particularly by the existence of air 

 bubbles throughout the vessels. 



Apart from its occurrence in infected subjects, the bacillus finds wide 

 distribution in nature, being found in soil, dust, and brackish water, 

 and in the normal intestinal tracts of human beings and mammals.' 



Morphology and Staining. — Bacillus aerogenes capsulatus appears 

 usually as a straight rod, not unlike the anthrax bacillus, but more 

 variable in length and somewhat thicker in proportion than the latter. 

 Occasionally bacilli are seen which are slightly curved, but these are 

 rare. The bacillus averages 3 to 6 micra in length, but may be three 

 or four times longer than this. More rarely the bacillus may appear so 

 short as to be almost coccoid. In artificial cultures it is usually thicker 

 and shorter than it is in animal tissues. The bacilli are generally single, 

 but are often seen in short chains. Their ends are usually slightly 

 rounded but, especially when in chains, may be almost square. Chain- 

 formation seems to occur chiefly in the blood, long chains never occurring 

 in artificial media. This characteristic is regarded by Welch as a dis- 

 tinguishing feature in differentiating this bacillus morphologically from 

 anthrax. In their first publication, Welch and Nuttall did not describe 

 spores as appearing in these bacilli. Dunham,^ however, in 1895, found 

 spores in cultures grown upon blood serum. The spores seem to be 

 formed only upon special media, rarely upon plain agar, never in the 

 animal body. The spores are oval, and may be placed centrally or 

 toward one end, one in each bacillus. 



The bacillus is non-motile, and doesfenot possess fiagella. It pos- 



1 Frankel, Cent. f. Bakt., xiii, 1893, p. 13. 



2 Welch, Bull. Johns Hopkins Hosp., xi, 1900, p. 185. 



» Although B. aerogenes capsulatus and B. phlegmonis emphysematosae are 

 separately described in many books, notably Migula's " System d. Bakteriologie,'' 

 the microorganisms have been shown beyond question to be identical and are 

 acknowledged to be so by Frankel himself. 



* Dunham, Johns Hopkins Hosp. Bull., -viii, 1897, p. 68. 



