1. The anatomical and viability characteristics of seeds of sixteen plant species were studied using the X-ray contrast method of Simak and Gustafsson (1954). The data revealed that the method can be used to assess reliably the germination potentialities of seed samples. Both mechanical injuries to the embryo and insect infestation could be readily detected. The presence of more than one embryo could also be easily seen in polyembryonic seeds.
2. By soaking seeds in BaCl2 solution prior to X-ray photography, the physiological soundness of aged seeds as well as of seeds stored without special precautions could be accurately determined. Seeds with massive endosperms such as those of cereals showed some impregnation of BaCl2 in the endosperm but they proved to be viable so long as the embryo remained free of impregnation and the endosperm did not show luminescence due to very heavy impregnation with BaCl2.
3. The X-ray dose delivered to seeds during the course of photography did not have any adverse effect on germination.
