532 THE ANAEROBIC BACTERIA 
A'arious strains of B. welchii differ markedly in their ability to pro- 
duce the soluble poison. Culture 617 D, obtained by Simonds in 
Belgium, appears to be the best known strain for this purpose. 
The nature of the soluble poison produced by the gas bacillus is as 
yet unsolved. It differs from the toxin of the tetanus, diphtheria or 
botulinus bacilli both in that it is found only in the early hours of 
growth, when multiplication is very rapid, and in that its effects are 
detectable, and even fatal within a minimum of two hours after injec- 
tion. The poison rapidly disappears upon prolonged cultivation. It 
becomes inactive a very few hours after it has reached its maximum 
concentration in cultures and here again it dift'ers from the classical 
toxins of diphtheria, botulism and tetanus which slowly accumulate for 
several days after the culture is started. 
Pathogenesis.— The pathogenesis of B. welchii is variable. The most 
characteristic lesion is the production of emphysematous gangrene, 
or "gas gangrene" in contused wounds, compound fractures and the 
infected wounds of warfare. Bulloch and Cramer^ have found that 
gas bacilli alone do not usually cause infection, but if small amounts of 
soluble calcium salts are added violent or fatal infections usually occur. 
The calcium salts do not add to the toxicity of the culture, but seem to 
produce a local breakdown of the defenses of the body against the 
bacteria. This same phenomenon holds for Vibrion septique, B, 
oedematiens, and B. tetani. The term kataphylaxis is proposed by 
Bulloch and Cramer to designate this condition of altered resistance to 
infection. It is also stated, but not confirmed,^ that the organism 
may be an incitant of acute articular rheumatism. In the intestinal 
tract^ the organism may incite or be associated with pathological con- 
ditions which vary in severity from mild diarrhea to extremely grave, 
or even fatal, dysenteric enteritis. Epidemics of such diarrhea appear 
to have been traced to milk in a few instances.'* Usually the organism 
does not become invasive in these diarrheas, but an occasional fatal 
case shows unmistakable evidences of invasion. In such instances the 
mucosa is enormously swollen, edematous and crepitant, and the bacilli 
may be demonstrated deeply invasive in the submucosa by the Gram 
stain. 
Epidemics of gas bacillus diarrhea, numbering hundreds of cases in 
the aggregate, have been reported, in which the Welch bacillus has been 
found in very great numbers.'' In this connection it is interesting to 
1 Proc. Roy. Soc, Series B., 1917-1919, 90, 513. 
2 Achalme: Compt. rend. Soc. de biol., 1891, 43, 651; 1897, 49, 276; Ann. Inst. 
Pasteur, 1897, 11, 845. 
' Howard (Johns Hopkins Hosp. Rep., 1900, 11, 66) states that the organism may 
develop in the gastric or intestinal mucosa, especially under the folds of the valvulae 
conniventes, and cause disintegration of the tissue. 
* Klein: Ann. Report Med. Officers to Local Government Board, London, 1897-1898, 
27, 210, 312. 
^ Kendall and Smith: Boston Med. and Surg. Jour., 1911, 164,306. Kendall, Day 
and Bagg: Loc. cit., 1913, 169, 741. Kendall and Day: Ibid., p. 753. Kendall: 
Ibid., May 20, 1915. Hewes and Kendall: Ibid., 1912, 166, 75. Simonds: Mono- 
graph 5, Rockefeller Inst., September 27, 1915, pp. 89-97. 
