ABSTRACT
Charles Richet (1850-1935) and Paul Portier, in 1902, observed that the injection of toxic extracts from the tentacles of various sea anemones or eel serum into dogs, which had 3 weeks previously received a smaller injection of the same antigen, produced severe symptoms, and in some cases death1. These two physiologists from the University of Paris had been asked by the Prince of Monaco to study the toxic properties of the Physalia found in the South Seas. What had been
intended to result in a state of protective immunity, had, much to their surprise, resulted in a state of hypersusceptibility of the tissues of the animals receiving the injections. The administration of this same extract into normal animals produced no adverse effect.
