Foard, DonaldE., and AlanH. Haber. (Biol. Div., Oak Ridge Natl. Lab.,3Oak Ridge, Tenn.)Anatomic studies of gamma‐irradiated wheat growing without cell division.Amer. Jour. Bot. 48(6): 438–446. Illus. 1961.—A morphological and histological study has been made of wheat seedlings growing without desoxyribonucleic acid (DNA) synthesis, mitosis, and cell division after gamma‐irradiation of the grain. The development of these seedlings parallels the normal development of unirradiated wheat in correlative growth of primordia and organs and in the production of highly differentiated cell and tissue types (e.g., trichoblasts, vascular elements, chlorenchymatous mesophyll, and cortical parenchyma). The absence of cell division makes these seedlings differ from unirradiated plants in several respects: no initiation of new organs; abnormal maturation of regions corresponding to the meristems; greater cell lengths. Guard cells, subsidiaries, and hair‐bearing cells are lacking, except in the apical 2–3 millimeters of the first leaf. Anatomic similarities of these plants to those treated with maleic hydrazide, including maturation to the tip of the roots, are discussed. The central cylinder of the upper pair of lateral seminal root primordia becomes highly differentiated with negligible elongation of the primordia. The occurrence of a high degree of differentiation after doses of radiation that produce extensive chromosome breakage indicates that in the absence of mitosis the chromosomes need not remain intact for the cells to continue differentiation. These studies show that such seedlings can be used to indicate the capacities of the cells in the embryo for differentiation without DNA synthesis, mitosis, and cell division.