It is a very rapid river, and subject to sudden swellings and overflowings, which cause great damage to the surrounding country.
The power exercised by the Leguminosae is associated with the presence of curious tubercular swellings upon their roots, which are developed at a very early age, as they are cultivated in ordinary soil.
If experimental plants are grown in ster1lized soil, these swellings do not appear, and the plant can then use no atmospheric nitrogen.
The swellings have been found to be due to a curious hypertrophy of the tissue of the part, the cells being filled with an immense number of minute bacterium-like organisms of V, X or Y shape.
Many aphides, &c., puncture the leaves, suck out the sap, and induce va:ious local deformations, arrest of growth, pustular swellings, &c., and if numerous all the evils of defoliation may follow.