THE RED ALG& 



239 



384. Uses of the brown algae. Some of the kelps (Lami- 

 naria japonica and L. angustata) are used as food by the Japa- 

 nese and Chinese. Some species of kelps are used as food for 

 cattle, and are spread upon the land for fertilizers by farmers and 

 peasants along the north Atlantic coast and in some European 

 countries. L. digitata is said sometimes to be employed in surgery. 

 Iodine is extracted from some kelps and rockweeds. 



THE RED ALG.E (RHODOPHYCE^)- 



385. General characters. The larger number of the red 

 algae grow in the sea, but a few grow in fresh water. They 

 possess chromatophores with chlo- 

 rophyll, but in most forms this is 



obscured by a reddish * or purplish 

 pigment. The various colors are red, 

 purple, brownish red, and green. 

 Some forms are filamentous, others 

 are more bulky and cord-like or 

 strap-shaped, while others are leaf- 

 like. Nearly all forms have a 

 greater or lesser amount of a gelat- 

 inous or slimy substance surround- 

 ing the parts of the plant. In the 

 method of reproduction, and in the 

 life cycle of some forms, they have 

 reached the highest stage of develop- 

 ment of any of the algae. Asexual 

 reproduction, where it occurs, takes 

 place by the formation of groups 

 of spores, four in each group (tetra- 

 spores), while in sexual reproduc- (After Vmes - ) 

 tion the fertilized egg develops a large number of spores. f While 

 these methods of reproduction are characteristic of the red algae, 



* Phycoerythrin. 



t Called carpospores, i.e., fruit spores, because the mass of spores is the 

 fruit. 



Fig. 202. 



A red alga (Nemalion). A, sexual 

 branches, showing antheridia (a); car- 



an almost "mature cystocarp (o)! 

 the disorganizing trichogyne (/) 



