ROCKWEEDS AND GULFWEEDS (FUCALES) 321 
The gametes are produced in a multicellular structure known 
as a gametangium, and, as in case of a sporangium, the gametan- 
gium may be formed from a cell within the filament or from a 
terminal cell on a short lateral branch. The small cubical cells 
composing a gametangium are packed closely together and each 
Fic. 276.— Portions of two fila- 
ments of Ectocarpus, showing repro- Fic. 277. — Plant body of 
duction. At s are shown spo- Fucus vesiculosus (X 3). In 
rangia, and between the filaments, the swollen tips are the con- 
azoospore. At gare shown a game- ceptacles in which the sex 
tangium and a single sperm and two organs occur, and at various 
sperms fusing at the right. Redrawn places occur bladder - like 
with modifications from Curtis. floats. 
produces a biciliate zodéspore-like gamete. After escaping the 
gametes fuse in pairs and form zygospores. In this plant such 
gradations occur between sporangia and gametangia and between 
zoospores and gametes, as to afford considerable support for the 
theory that gametes are simply zodéspores which are too small 
to function alone. 
Rockweeds and Gulfweeds (Fucales).—In this order the 
plant body may reach a meter in length, but is usually much 
