The relation between the development, structure and functioning of the nodules on Vicia faba as influenced by the presence or absence of boron in the nutrient medium

The problems connected with the nodules that are produced by Bacillus radicicola on leguminous plants fall naturally into four divisions: (a) The life of the organism in the soil and the causes leading to its arrival at the usual point of infection—the root hair. (b) The entry of the organisms into the tissues of the plant. (c) The causes leading to the formation and development of the nodules after the entry of the organism into the plant. (d) The physiological processes within the nodule, especially those leading to the fixation of elemental nitrogen. The life of the organism outside the plant and the causes leading to its initial entry into the tissues do not concern the present paper, which deals with the relation between the organisms within the nodule, and the anatomy and physiology of the tissues of the host plant.