526 THE ANAEROBIC BACTERIA 
capsulatus. It appears to be identical with B. phlegraones emphy- 
sematosae,' B. perfringens,- and B. emphysematis vaginae.^ B. 
enteritidis sporogenes/ Granulobacillus saccharobutyricus immobilis 
liquefactiens,^ and other, less well known anaerobic organisms appear 
to be mixtures of anaerobic bacilli, containing B. welchii contaminated 
with putrefactive organisms, most frequently in all probability, B. 
sporogenes of Metchnikoff. B. welchii is frequently referred to as the 
"gas bacillus" in the United States, not, however, because it is a very 
active fermenter of carbohydrates, but because of its etiological 
relationship to the causation of "foamy organs" and gas gangrene.** 
The first isolations of the organism, both by Welch, by Frankel and 
by Lindenthal, were from cases which belong to the gas gangrene group. 
B. welchii is invariably referred to by French investigators as B. 
perfringens; the name B. aerogenes capsulatus has been the customary 
designation in the United States, but the present tendency both in 
England and in the United States is to refer to it as B. welchii. 
Morphology.— B. welchii is a large bacillus measuring from 0.8 
to 1.2 micron in diameter, and from 2 to 6 microns in length, with 
rather pronounced square-cut ends. It normally occurs singly and in 
pairs, both in culture and in the tissues; in older fluid cultures long 
filaments are sometimes found. Also short, nearly coccoid elements 
are not infrequently- seen, and degeneration forms which are quite 
varied in appearance. The shorter elements appear to predominate 
among those bacilli which are found in the bloodvessels,'^ and under 
these conditions the organisms exhibit a distinct tendency to remain 
adherent in chains of varying length.* 
The organism is non-motile and possesses no flagella.'-' It forms 
capsules in the animal body, and occasionally in albuminous media. 
Spores are produced but the ability to sporulate varies with the strain 
under observation.^" i\ll cultures, however, which have not been 
injured by exposure to prolonged unfavorable conditions will sporulate 
in a favorable en\^ronment. 
The spores are oval, somewhat less in diameter than the vegetative 
form of the organism, and they are usually central or subterminal. 
But one spore is formed in a single organism. Spores do not appear 
to form in the tissues or fluids of the body. They do not occur in media 
containing utilizable carbohydrate. In protein media, however, as 
inspissated blood serum, egg, cooked meat medium (freed from glucose) 
1 Friinkel: Centralbl. f. Bakteriol., 1893, 13, 13. 
- Veillon and Zuber: Arch, de med. exper. ct d'anat. path., 1898, 10, 517. 
' Lindenthal: Wien. klin. Wchnschr., 1897, 10, 3, 1109. 
" Klein: Centralbl. f. Bakteriol., 1895, 18, 737. 
6 Schattenfroh and Grassberger: Centralbl. f. Bakteriol., II Abt., 1899, 5, 209 
Munchen. med. Wchnschr., 1900, 47, 1032, 1077; Arch. f. Hyg., 1902, 42, 251. 
^ Weinberg and Seguin: La Gangrene gazeuso, Paris, 1917. 
' Welch: Johns Hopkins Hosp. Bull., 1900, 11, 185. 
s Henry: Jour. Pathol, and BacterioL, 1916-1917, 21, 344. 
9 Klotz and Holman, however, report a motile culture (Jour. Infec. Dis., 1911, 9, 251). 
1" Dunham: Johns Hopkins Hosp. Bull., 1897, 8, 68, 74. 
