Structure of Plant Cells with Special Reference to Lower Plants

The fine structure of the chloroplasts of various algae were investigated with an electron microscope.Materials used for the present investigation included 21 species from 7 divisions of algae. In addition to 4 species from 2 divisions which have been reported previously by the author, 25 species from 9 divisions were studied with regard to the structure of their chloroplasts.Of the 9 divisions, the Cyanophyta and Glaucophyta were found to have no chloroplasts while the others had. The chloroplasts of these latter algae were classified into several groups in relation to the lamellar structure of their chloroplasts; these groups are (1) chloroplasts with two lamellate layers, (2) chloroplasts with four lamellate layers and (3) chloroplasts with granalike structure. The Rhodophyta belong to the first group, the Phaeophyta, Pyrrophyta, Chrysophyta and Euglenophyta to the second group, and the Charophyta and Chlrophyta to the third group.These groups may be subdivided an the basis of the presence or absence of pyrenoids.Several lamellae, which are similar in their appearance to those of the chloroplasts are seen in the pyrenoids.Pyrenoids are classified into five types in relation to the lamellae and the assimilation products.