754 PATHOGENIC MICROORGANISMS 



of B. Wclchii failed to agglutinate with this scrum, and ten others 

 agglutinated only in a dilution of 1-20. The agglutination reaction 

 for the identification of anaerobes has so far proved unsatisfactory. 

 TOXIN PRODUCTION. Klose in 1916 12 reported the isolation of a 

 toxin from B. Welchii prepared by growing B. Welchii for fourteen 

 days in a 5 per cent glucose broth. The antitoxin produced by 

 injections of this toxin only protected guinea-pigs against three 

 lethal doses of B. Welchii cultures. The antigenic properties of this 

 toxin were too feeble to consider it a true toxin. The most important 

 contribution to the bacteriology of B. Welchii was made in 1917 

 by Bull and Pritchett 13 who were able to prepare a soluble toxin 

 which, when injected into a suitable animal, produced a potent 

 antitoxin possessing protective and curative properties against B. 

 Welchii infections, in animals. One c.c. of antitoxin per 100 grams 

 body weight injected subcutaneously protected guinea-pigs against 

 300 lethal doses of culture. 14 The production of a powerful toxin 

 (0.3 c.c. to 3 c.c. being the M. L. D. for a pigeon of 300 gr. injected 

 intramuscularly) depended on the" virulence of strain, a short in- 

 cubation period, twenty-one to twenty-four hours, and the presence 

 of fresh muscle and glucose in the broth. Bull and Pritchett found 

 no variations in the ability of different strains of B. Welchii, irre- 

 spective of the source of the culture, to produce toxin. The toxin 

 production of less active strains could be increased by raising the 

 virulence of the culture by animal passage. Caulfield in a recent 

 paper 15 finds that he does not get good toxin production unless the 

 virulence of his strain is such that 0.02 c.c. of supernatant fluid 

 of a young broth culture will kill a 300 gr. pigeon. Caulfield also 

 emphasizes the importance of fresh muscle in the culture medium, 

 although DeKruif and the Hygienic Laboratory in Washington 

 obtained good results by substituting chopped veal which can be 

 autoclaved, for the fresh muscle tissue. The most potent toxins, 

 however, seem to be obtained by inoculating the infected muscle 

 of a pigeon dying of a B. Welchii infection directly into the medium 

 to be used for toxin production, or, at most, allowing one short 

 culture generation (ten hours) to intervene between the last animal 

 passage and the inoculation of the broth for toxin. By preparing 



12 Klose, Munch, med. Woch., Bd. 63, 1916, 723. 



13 Bull and Pritchett, Jour. Exper. Med., 26, 1917, 867. 



14 Bull and Pritchett, Jour. Exper. Med., 26, 1917, 867. 

 Caulfield, Jour. Infec. Dis., 27, 1920, No. 2. 



