276 



Introduction to Botany. 



eight in number, are borne in small sacs growing out from 

 the walls of the conceptacle (see Fig. 139); and the 

 sperms are formed in elongated cells produced on hair-like 

 outgrowths. Both eggs and sperms become discharged 



^nriQSi**^ 



Fig. 139. 



Fucus. A, portion of a frond ; B, section through) a conceptacle ; C, oogonium 

 with eggs : D, antheridium with sperm cells ; E, an egg with sperm cells swim- 

 ming about it. After Thuret. 



from their conceptacles into the surrounding water, and 

 the sperms seek the eggs, being able to swim about by 

 means of two cilia. One of the sperms penetrates the egg 

 and effects its fertilization. The egg then forms a wall 

 about itself and is capable of immediate germination. 



Some of the marine Algse closely related to Fucus attain 

 as much as a hundred feet in length, and produce lateral 



