312 



CHARACE&. 



PART II. 



SECTION V. 



CHAEACEJB. 



THE Characese are submerged annual water plants, 

 growing in stagnant pools and ditches rather than in 

 running streams. It is a small order 

 containing but three genera, but the 

 numerous species are dispersed all over 

 the world, especially in temperate cli- 

 mates. The genera found in this 

 country are Mtella and Chara. The 

 Nitella flexilis (fig. 40) may be taken 

 as a representative of the order. Its 

 stem or axis is formed of very long 

 cylindrical transparent tubes, joined 

 by their flat ends, and surrounded at 

 each junction by a whorl of long tubes 

 which are forked or trifid at their ex- 

 tremities. In some species the branches 

 are jointed, and have whorls precisely 

 like those on the main axis. On the 

 internal surface of the tubes, which 

 are sometimes several inches in length, 

 there are four longitudinal bands 

 parallel to the axis of the tubes, which 

 are occasionally twisted : two of these 

 bands are broad and covered with oval 

 green particles ; while the other two are narrow, trans- 

 parent, and colourless. Each tube is filled with a limpid 

 semifluid liquid, in which pale green particles and jelly- 



Fig. 40. Nitella 

 flexilis. 



