“…I t has been suggested that the preinduction period may be related to the initial events involved in the fixation of antigen by the cells (Kohn, 1951), to the localization of the antigen in the antibody-forming sites or to the early metabolism of the antigen (Taliaferro, Taliaferro, and Janssen, 1952), or to the persisting adaptation of the gamma-globulin-synthesizing mechanism to the specific antigen (Dixon, Talmage, and Maurer, 1952). From the cellular standpoint, it has been suggested that irradiation damages a precursor of the antibody-forming cells or prevents certain cells from reaching a critical stage at which they can react properly with the antigen (Talmage, 1955). So far, no marked difference has been found in the gross localization of antigen following severe total-body X irradiation (Fitch et al, 1953, andIngraham, 1955), but this finding does not necessarily contradict the ideas of highly specific types of localization implied in the above suggestions.…”