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 
