CHAPTER VII. 

 CLASS III. THE BED ALG^E (Wiodophycece) . 



THESE are among the most beautiful and interesting mem- 

 bers of the plant kingdom, both on account of their beautiful 

 colors and the exquisitely graceful forms exhibited by many 

 of them. Unfortunately for inland students they are, with 

 few exceptions, confined to salt water, and consequently fresh 

 material is not available. Nevertheless, enough can be done 

 with dried material to get a good idea of their general appear- 

 ance, and the fruiting plants can be readily preserved in strong 

 alcohol. Specimens, simply dried, may be kept for an indefi- 

 nite period, and on being placed in water will assume perfectly 

 the appearance of the living plants. Prolonged exposure, how- 

 ever, to the action of fresh water extracts the red pigment 

 that gives them their characteristic color. This pigment is 

 found in the chlorophyll bodies, and usually quite conceals the 

 chlorophyll, which, however, becomes evident so soon as the 

 red pigment is removed. 



The red seaweeds differ much in the complexity of the 

 plant body, but all agree in the presence of the red pigment, 

 and, at least in the main, in their reproduction. The simpler 

 ones consist of rows of cells, usually branching like Clado- 

 phora; others form cell plates comparable to Ulva (Fig. 30, 

 (7, D) ; while others, among which is the well-known Irish 

 moss (Cfltondrus), form plants of considerable size, with pretty 

 well differentiated tissues. In such forms the outer cells are 

 smaller and firmer, constituting a sort of rind ; while the inner 

 portions are made up of larger and looser cells, and may be 

 called the pith. Between these extremes are all intermediate 

 forms. 



49 



