Cytology of Dormancy in Phaseolus and Zea

Abstract

1. The cellular morphology of the dormant and the germinated seed was compared in both the bean and corn. Seeds were fixed in various fluids, and after each type of fixation were stained by both iron haematoxylin and the Feulgen reaction. 2. In the dormant state the cell is plasmolyzed; the nucleus has an irregular form, apparently lacking a membrane or limiting structure; the nucleolus is not optically differentiated by fixation although it may stain intensely with iron haematoxylin. The vacuoles are small, and the mitochondria are small granules or spheres. 3. At germination the cell becomes turgid; the nucleus regains a normal spherical form and the boundary becomes definite; the nucleolus becomes optically differentiated even when unstained as by the Feulgen reaction, and shows a vacuolate structure. The vacuoles of the cytoplasm enlarge, and the mitochondria elongate into rods or filaments. 4. Prior concepts regarding the chromatin of the dormant cell as having migrated centrifugally (Hickernell) or centripetally (Kater) are rejected on the basis of the Feulgen reaction.