DEVELOPMENT OF PLANTS 189 



is effected, for Farmer observed that the male cells swarm about 

 the female cells for a time and then suddenly swim away " like 

 a flock of frightened birds." As soon as fertilization has been 

 effected, the gametospores become invested with a cell wall and 

 attached to the rocks. Cell division now proceeds rapidly and 

 soon establishes the characteristic thallus of the plant (Figs. 124, 

 D ; 121, C). Fucus is a very prolific plant and the reproduction 

 process can be observed at almost any time. After the plants 

 have been exposed for several hours by the low tide the male 

 and female gametes will often be found forming orange yellow 

 and olive green drops at the mouth of the cavities. In this 

 condition the entire process of fecundation and early stages of 

 germination can be studied by transferring a bit of these two fluids 

 to a drop of sea water on a slide and studying them under a 

 microscope. The differentiation of the gametes of Fucus is an 

 interesting one because it represents the stage where the female 

 gamete has become motionless, but is not retained in the mother 

 cell as in Vaucheria and Oedogonium. 



No resting spores are found among the brown algae. This 

 may be connected with the more uniform conditions that ob- 

 tain in the sea where they are not exposed to the dangers of 

 desiccation as in fresh water forms. It is also noteworthy, that 

 although the reproduction organs are, on the whole, more com- 

 plex, fertilization is of a more primitive character than among 

 many of the green algae, in that the fusion of the gametes is 

 effected outside of the gametangia. 



CLASS C. RED ALGAE OR RHODOPHYCEAE 



74. General Features. The Red Algae are largely marine 

 plants. Unlike the brown algae, they reach their greatest de- 

 velopment and abundance in the warmer waters of the temperate 

 and tropical seas and are usually found attached to various ob- 

 jects below tidal marks. Their red pigments probably adapt 

 them to the feeble illumination of the deep waters in which they 

 generally occur. They range through a great variety of forms, 

 from delicate filaments or flattened ribbon-like bodies to struc- 



