“…A further reason for the change of medium was that mild allergic symptoms have been reported in a few persons, mainly after second injections of toxoids prepared from broth containing Witte peptone (Whittingham, 1940;Parish andOakley, 1940. Cooke, Hampton, Sherman andStull, 1940;Cunningham, 1940); these manifestations are apparently due to the peptone. We do not claim that the substitution of a medium which does not contain Witte peptone will obviate all allergic symptoms, although so far none has been reported to us.…”