PLANTS FOR. 35 



bodies, and are interesting objects under the 

 microscope. One of the most remarkable pro- 

 perties of the Charas is the facility with which 

 the movements of the fluids in their cells may 

 be witoessed through the- microscope. All that is 

 necessary in order to observe them is to place a 

 portion of the plant on a piece of glass or in an 

 animalcule-cage, and the circulation quickly be- 

 comes apparent. This phenomenon is best seen in 

 the species of Nitella, as they need no preparation 

 of the branch previous to examination. In Char a, 

 it is first necessary to scrape off a layer of cellular 

 matter, which is frequently hard and stony, and 

 which collects on the surface of all their branches. 

 This is the great distinction between the species 

 of Chara and Nitella. In Chara the whole plant 

 is more or less opaque and brittle, and the pri- 

 mary cells are invested with a layer of cells 

 which are arranged in a spiral manner along 

 the primary branches. In Nitella, on the con- 

 trary, the whole plant is more or less pellucid, 

 and the primary cell-membrane is not covered 

 with any secondary investment. 



THE FLEXILE NITELLA (Nitella flexilis) is the most 

 common form of Nitella, and is not unfrequent 

 in pools, ponds, and lakes. It may be known by 

 the branched character of its stems, and its 

 smooth, glossy, pellucid appearance. 



THE COMMON STONE WORT (Chara vulgaris), Fig. 11, 

 is the most common species of the family. It is 

 found in ponds, ditches, and slow streams, and 

 may be known by its yellowish-green hue. It has 

 a smooth stem, but it may be easily known from 

 the Nitellas by its opaqueness and brittleness, 

 and the spirally-striated markings upon the stem. 

 The other species of Nitella and Chara are not 

 so common. 



