i6 



MORPHOLOG Y. 



270. The red algae (Rhodophyceae). The larger number of the so-called 

 red algse occur in salt water, though a few genera occur in fresh water. 



Fig. u 9 . 



Portion of plant of fucus showing 

 conceptacles in enlarged ends ; and 

 below the vesicles (Fucus vescicu- 

 losus). 



Fig. 120. 



Section of conceptacle of fucus, showing 

 oogonia, and tufts of antheridia. 



(Lemanea grows only in winter in turbulent water of quite large streams. 

 Batrachospermum grows in rather slow-running water of smaller streams. 

 Both of these inhabit fresh water.) The plants of the group possess chloro- 

 phyll, but it is usually obscured by a reddish or purple pigment. 



271. Gracillaria Gracillaria is one of the marine forms, and one species 

 is illustrated in fig. 126. It measures i$-2Ocm or more long, and is pro- 

 fusely branched in a palmate manner. The parts of the thallus are more or 

 less flattened. The fruit is a cystocarp, which is characteristic of the rhodo- 



