TAXONOMY 



243 



develop into new Ectocarpus plants. Along the filaments several 

 branches will be seen. Some of these have undergone division into 

 several cells and these again into still smaller cells until many-celled 

 chambers have resulted, which are called plurilocular sporangia. 



FIG. 118. End of large branch of Fucus vesiculosus (natural size); e, receptacle; 



b, air bladder. 



Each cell of a plurilocular sporangium contains a gamete or sexual 

 cell, which resembles in many details a zoospore. When the spo- 

 rangium matures these gametes are discharged into the salt water. 

 They fuse together in pairs and form zygospores. Each zygospore 



