“…Spleen cells from thymus-deprived mice do not respond in vitro to sRBC (Hosier, Fitch, Rowley and Davies, 1970;Munro and Hunter, 1970;Rosenoer, Biano and Brown, 1970;Hirst and Dutton, 1970;Aden, Reed, and Jutila, 1972). Hosier et a l. (1970), Rosenoer et a l. (1970) and Hirst and Dutton (1970) determined that the cellular defect in thymectomized mice was in the non-adherent cell population. Others (Doria, Martinoz, Agarossi and Dipietro, 1970;Munro and Hunter, 1970;Aden, Reed and Jutila, 1972) reported that addition of thymocytes to spleen cell cul tures of thymus-deprived mice restored responsiveness toward sheep erythrocytes.…”