BACILLUS WELCH 1 1 533 
note that Bull^ has found that the sohihle poison of the j^as bacillus 
produces serous edema, violent peristalsis associated with diarrhea, 
and not infrequently vomitino;, upon introduction into exi)eriniental 
animals.- 
The most important effects of the gas bacillus, aside from the 
mechanical consequences of the evolution of gas under pressure,^ are 
in association with its soluble poison, which produces hemolysis in the 
living animal, and extensive necrosis of muscle. Apparently the coarser 
muscles, as the glutei, are more readily penetrated than the more 
finely constructed muscles. The tissue becomes edematous, friable, 
and necrotic. Association of the gas bacillus with B. sporogenes 
increases materially the toxicity of the former.^ The minimal fatal 
dose of the poison of B. welchii varies from 0.25 cc. to 1 or more cc. 
Antitoxin.— I3ull and Pritchetf^ have succeeded in producing a specific 
neutralizing serum both for the poison of the gas bacillus, and for the 
organism itself, by injecting increasing amounts of the twelve to 
eighteen hour filtrate of actively growing cultures of 617 D into large 
animals. The titer of such a serum may be as high as 5()()() to ()()()() 
units (horses), but as a rule it rarely exceeds 1000 to 2000 units after 
eight weeks' intensive immunization." Available evidence indicates 
that the antiserum, used early, has distinct value in the treatment of 
infected wounds. '^ 
Immunity Reactions. — 1. Ilcvwlysins.— Many strains of B. welchii 
form hemolysins which will liberate hemoglobin from the erythro- 
cytes of man, horses and other herbivorous animals, the dog, guinea- 
pig, rabbits, white rat and pigeons. The hemolytic substance is 
thermostabile, being destroyed by an exposure to 70° C. for thirty 
minutes, and it is found in significant amounts only in young cultures, 
from twelve to eighteen hours. Longer incubation leads to its dis- 
appearance. (In this respect it suggests the soluble hemolysin of Str. 
hemolyticus.) The hemolytic action is not due to the acid reaction 
of the culture in which it is developed; carefully neutralized filtrates 
of cultures are nearly as active as those which are unneutralized. 
Filtration of cultures through Berkefeld filters reduces the amount 
of hemolysin \'ery materially. Henry ** has shown that the hemolysin 
is very toxic for mice. Antiserum contains an appreciable amount of 
specific antihemolysin. 
2. Pircipifins.—McCsimpheW^ has found that the injection of cul- 
tures of the gas bacillus into rabbits leads to the formation of specific 
precipitins of considerable potency. 
1 Loc. cit. 
2 Vomiting applied only to pigeons; apparently guinea-pigs and rabbits do not vomit. 
' Taylor: Loc. cit. 
« Bulloch and Cramer: Proc. Roy. Soc, London, Series B., 1919, 90, 51:5. 
* Loc. cit. 
^ Medical Research Committee, Special Report 39, 1919. 
' Nevin: Compt. rend. Soc. de biol., 1919, 82, 140. Vincent and Stodel: Compt. 
rend. Acad. Sci., 1919, 168, 188. 
* Loc. cit. ' Loc. cit. 
