Of the first group, Euglena (Fig. 9), may be selected as a type.
Many of these minute plants develop locomotion and a degree of sensitiveness (Diatoms, Peridinea, Euglena, etc.).
The principal species are the Euglena viridis and the Euglena pyrum.
In this way Engelmann was able to determine the evolution of oxygen by Euglena and by chlorophyl granules.
Among unicellular green ...