So 



MORPHOLOGY 



Sex organs. — In the thallus body, often at the tips of special branches, 

 there occur the conceptacles, which are chambers, each of which opens 

 to the surface by a small porelike opening. Within these conceptacles 

 the antheridia and oogonia are produced, the two organs appearing in 

 the same conceptacle or in different ones (figs. 128, 129). The concep- 

 tacles contain also numerous branching filaments {paraphyses), which 



129 

 Figs. 128, 129. — Fucus: 128, an antheridia] 

 conceptacle; 129, an oogonial conceptacle. — After 

 Thuret. 



Figs. 130, 131. — Fucus: 



130, the oval antheridia borne 

 on a branching paraphysis; 



131, the laterally biciliate 



- After Thuret. ■ 



arise from the cells bounding them. The antheridia are borne as lateral 

 branches of these paraphyses and arc produced in great profusion (figs. 

 130, 131). They are oval cells that produce numerous small laterally 

 biciliate sperms. The oogonium is a large, globular, stalked cell and 

 commonly produces eight eggs (oospheres) (figs. 132-136). There are 

 related genera whose oogonia produce four or two eggs, and often only 

 one; but in all of them eight nuclei appear. Such evidence suggests 



