Published online by Cambridge University Press: 15 May 2009
The production of soluble toxic substances in broth cultures of these bacteria is well known. Berkefeld nitrates of such cultures are usually toxic for the rabbit upon intravenous injection. A review of the literature has been given by Ecker (1917, 1925) and by Branham (1925). Subsequent studies of these workers have shown that Berkefeld filtrates of synthetic medium (Braun and Cahn-Bonner, 1921) cultures yielded toxic substances inducing a similar reaction in the rabbit. Little is known concerning the nature of these substances beyond that they are relatively thermostabile; on dialysis of the broth culture nitrate the toxin is withheld within the collodium sac.