324 THALLOPHYTES 



It is now evident that among the Brown Algae there is more 

 differentiation of plant body and more specialization in sexuality 

 than among the Green Algae. Except in their lowest forms, they 

 show no affinities with the Green Algae and consequently are 

 supposed to have originated independently and probably from 

 such organisms as gave rise to the Green Algae. Unlike the Green 

 Algae they show no evidence of having led to higher forms. 



Red Algae (Rhodophyceae) 



These Algae are mainly marine forms, although some forms 

 occur in streams. Besides the green they have a red pigment 

 called pMjcoerythrin which determines their color. Some also 



Fig. 280. — A finely branched Red Alga. Natural size. 



have a blue pigment, phycocyanin. They are not so bulky as the 

 Brown Algae, but they exceed them in number of species and are 

 much more diversified in form. Some are mere filaments no 

 larger than Vaucheria. They live mostly below low water mark 

 and often at depths of more than 100 feet in clear waters. 



The plant body, commonly only a few inches in length, is flat, 

 thin, and flexible and usually much branched. Some kinds are 

 finely branched, as the Sea Mosses noted also for their beautiful 

 colors of red, violet, and purple {Fig. 280). As in the Brown 



