102 PLANT LIFE. 



asexual generations are produced during the summer, the 

 sexual condition developing towards the autumn and 

 forming resting-spores, which enable the species to survive 

 the winter or season unfavourable for active vegetation. 



Confervoidese Isogaiiise. 



In the present class we first meet with typical multi- 

 cellular plants, consisting for the most part of simple or 

 branched single rows of cells, placed end to end. Increase 

 in length takes place by the repeated bipartition of the 

 terminal or apical, and sometimes also by the division of 

 intercalary cells. In some species the terminal cell is 

 prolonged into a slender, tapering colourless hair. This 

 character is well seen in the genus Draparnaldia, a very 

 beautiful alga not uncommon under the form of bright 

 green, gelatinous-feeling small masses attached to other 

 plants, twigs, etc., in clear fresh water. Most of the species 

 included in the present class inhabit fresh water, but a few 

 occur in brackish water, or in the sea. As a rule the 

 plants are bright green, but in the genus Chrookpus the 

 green colour is masked by a bright orange or red colouring- 

 matter. Chrookpus aureum is not uncommon on rocks and 

 walls, forming bright orange, velvety patches, sometimes 

 of considerable extent. Several nuclei are usually present 

 in each cell, as in the Multinuckata ; but the members of 

 the present order differ from those of the last-mentioned 

 in being distinctly multicellular. 



The most general form of reproduction is asexual, by 

 ciliated zoospores. A second form of asexual reproduction 

 is by the formation of non-motile cells, which often form 

 resting-spores. Such non-motile reproductive bodies when 

 formed by rejuvenescence of the contents of a mother-cell 



