260 



GENERAL MORPHOLOGY OF PLANTS 



bodies attached by a stalk to the wall of the conceptacle. The 

 eggs are set free by the rupture of the wall, and escape to the 

 outside. The sperm cases are small elliptical bodies borne as 

 branches on very much branched filamentous outgrowths from 



Fig. 209. 



Antheridia of Fucus on 

 branched threads. 



Fig. 210. 



Antheridia of Fucus with 

 escaping sperms. 



Eggs of Fucus surrounded 

 by sperms. 



the wall. Each sperm case develops a large number of small 

 biciliate sperms, which also escape to the outside in the sea water. 

 Here they swim among and around the eggs, often causing them to 

 revolve. One sperm finally enters and unites with the egg 

 nucleus. The fertilized eggs which reach favorable localities 

 start to grow within a day and develop new rockweed plants. 



397. Sargassum. This is another rockweed which is inter- 

 esting because of the large number of small bladder-like floats 

 developed as lateral outgrowths, in addition to the thin blades and 

 the reproductive branches. Sargassum is sometimes spoken of 

 as gulf weed. Large numbers of them are broken away by the 

 waves, from the rocks on the shores of the West Indies, and 

 are carried by the gulf streams to the open sea between the 2oth 

 and 4oth parallels of latitude, where they often accumulate in 

 vast numbers, forming what are called "Sargasso seas," and some- 

 times interfere with navigation. Here they grow vegetatively, 

 but are not known to fruit under these conditions. 



