Book excerpt: Discovered the extent of morphological variation of the individual species of Oscillatoriaceae, a group of algae which cover a substantial part of the earth¿s barren surfaces & constitute a goodly proportion of the conspicuous plants in its bodies of water. The capabilities of these algae for structural change during natural growth in diverse habitats, & in a single habitat as the environment changes, have been ignored. Plants deviating from the ¿typical¿ as a result of such variability have been interpreted as atypical or anomalous for the species concerned or have been described forthrightly as taxa new to science. The outcome of this investigation is comparable with that of a similar study of the coccoid Myxophyceae by Drouet & Daily (1956). Illustrations.