The internodal cortical parenchyma of etiolated and normal broad bean seedlings has been examined by techniques appropriate to normal and polarized light, X-ray and electron diffraction, and the electron microscope. No fundamental differences in fine-structure were observed, the cellulose being in both cases organized into well-marked but only feebly crystalline microfibrila weakly oriented in a transverse direction. The cells produced in darkness, though larger and showing a reduced tendency to differentiate into collenchyma, are fundamentally normal in type; and the gross morphological differences must primarily be sought in a changed disposition of the products of cell-division at the apex.