ALG^ 71 



A remarkable characteristic of the class is the absence 

 of the motile reproductive cells so common in the brown 

 and green algae. In the lowest members of the class, 

 the Bangiacese, the reproductive cells are said to show 

 a slight amceboid movement, but in all the others even 

 such movement is quite wanting. Another peculiarity 

 is the very evident protoplasmic connections between 

 the cells of the thallus, these being constantly present 

 in all but the lowest types. These connections have 

 the form of extremely delicate filaments joining the 

 protoplasmic bodies of adjacent cells (Fig. 19, A). 



They all possess in addition to the chlorophyll an 

 additional pigment, which, in most forms, is a more or 

 less pronounced red. This pigment (phycoerythrin) 

 is least developed in the fresh-water species, which 

 show a more or less decided green tinge, olive or black- 

 ish rather than red. Many of the salt-water species, 

 however, show a brilliant rose-red or purple color, to 

 which they owe much of their beauty. This red pig- 

 ment is soluble in fresh water and when it is extracted 

 from the plants the chlorophyll-green becomes visible. 

 The phycoerythrin seems to be related in its nature to 

 chlorophyll, and probably is associated with it in the 

 process of photo-synthesis. 



The red algse are small plants compared to the 

 gigantic kelps, but are as a rule larger than the green 

 algae. Some are exceedingly delicate, consisting of 

 simple or branching filaments much like some of the 

 Confervacese. Others are composed of single plates of 

 cells, which form an excessively delicate, filmy thallus. 

 Some, however, like the common Irish moss (Chondrus), 

 and other species which grow where they are exposed 



