Within the last seven or eight years several investigators have attempted to discover a prophylactic or therapeutic agent for typhoid fever based on antibacterial or antitoxic lines. In some cases a protective inoculation with a weakened virus has been employed, as in the protective inoculation of Wright, while in other instances an antitoxic serum has been used for curative purposes. Theoretical objections have been raised as to the possibility of making use of an antitoxin, on the ground that the typhoid bacillus does not excrete a soluble poison like the diphtheria bacillus, but forms instead an intracellular toxin. On this point, however, there is a good deal of disagreement, and some of the recent work on this subject seems to show that the typhoid bacillus produces a soluble toxin as well as an intracellular one.
One of the earliest observers who attempted to produce an antitoxin to neutralize the typhoid