THE RED ALG& 



265 



growth of long filaments, with one or more neighboring cells 

 on other branches. This is probably for the purpose of obtain- 

 ing a greater amount of nutriment for the development of the 

 fruit spores, which are formed "by the growth and branching of 

 this neighboring (auxiliary) cell. 



404. Uses of the red algae. 

 Many of the red algae develop 

 quantities of a gelatinous sub- 

 stance in their tissues. Several of 

 these are used for the manufac- 

 ture of gelatines and agar-agar. 

 Gracillaria lichenoides and ivrightii 

 are used for this purpose, the 

 former species occurring along 

 the coasts of China and India. 

 Some are also used for food. The 

 " Irish " moss, Chondrus crispus, 

 widely distributed in the northern 



Atlantic ocean, is used for food and for medicinal purposes. 

 Another plant used for similar purposes is Gigartina mamillosa, 

 in the Atlantic and Arctic oceans. 



Fig. 217. 

 Irish moss (Chondrus crispus). 



