Abstract
In broad bean, the nodule bacteria of roots enter the host plants through their root hairs and remain rod-shaped during the early period of infection. But, with the development of the nodules, the bacteria assume a characteristic form, e. g. T, V or Y shape, which are known as bacteroids. Hence, in the nodule bacteria of roots, we can recognize following two forms. 1. Moving form : Rod-shaped. 2. Settling form : Known as bacteroid, mostly T, V or Y shape. The transformation of nodule bacteria from the moving form to the settling one seems to be connected with the nitrogen fixation which is performed by the bacteria. Perhaps, the transformation may occur to facilitate the function of nitrogen fxation. In some species such as soy bean, the bacteria do not assume the transformation during the nitrogen fixation. But, they are also desirable to call the non-transformed bacteria as bacteroids. Because, bacteroids do not mean the bacteria transformed but the one settled for nitrogen fixation.
