. Biology . ne motile, the other not. As unicellularforms they are allied to a large number of low types of plantsincluded in the group known as Algae, in which some formsare included which cannot be accurately determined as plantsor as animals. Some of these, like the Peridiniales or Dino-flagellata and the Volvocidae, are included by botanists asplants, by zoologists as Pleurococcus is widely distributed in damp places, whereit exists as a green covering to stones, tree trunks, ground, cell is composed of protoplasm differentiated into cyto-plasm and nucleus, and contains
. Biology . ne motile, the other not. As unicellularforms they are allied to a large number of low types of plantsincluded in the group known as Algae, in which some formsare included which cannot be accurately determined as plantsor as animals. Some of these, like the Peridiniales or Dino-flagellata and the Volvocidae, are included by botanists asplants, by zoologists as Pleurococcus is widely distributed in damp places, whereit exists as a green covering to stones, tree trunks, ground, cell is composed of protoplasm differentiated into cyto-plasm and nucleus, and contains minute grains of coloring matter, chlorophyll, is uniformly distributedthroughout the cell, which, finally, is covered by a transparentcoating of cellulose, a characteristic plant product similar inchemical composition to starch but with a different arrange-ment of molecules. Reproduction occurs by simple division,the daughter cells separating when formed, or remaining to- UNICELLULAR PLANTS 107. Fig. 40.—Pleurococcus, from the bark of an elm tree in active vegetation. A,Dried cells; B, dixasion within a cyst; C, cyst contents divided into four cells;D, motile form of Protococcus (?). (From Sedgwick and Wilson.) 108 PLANTS, THE FOOD OF ANIMALS gether in groups of two, three or more cells, sometimes eight ornine forming a loosely arranged colony. The union is only
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