340 A TEXTBOOK OF GENERAL BOTANY 


eo 
GOB BO00 
as GeaRs 
Fig. 352. Ectocarpus 
This is a filamentous brown alga that 
reproduces sexually by the forma- 
tion of a large number of gam- 
etes in gametangia, shown in the 
drawing to the left as oval struc- 
tures. Hctocarpus reproduces asex- 
ually by zodspores formed singly 
in zodsporangia, as shown in the 
drawing at the right. (x 145) 
(Fig. 352). Asexual reproduction 
is by means of zoospores which are 
produced singly in zoodsporangia 
(Fig. 852). Sexual reproduction 
is due to gametes which are formed 
in large numbers in gametangia 
(Fig. 352). <All the gametes are 
similar in appearance. 
Fucus (Fig. 853) and Sargassum 
(Fig. 351), of the order Fucales, 
are well-known examples of more 
complex brown alge. Sargassum 
is sometimes found floating in the 
sea in large quantities. A large 
tract of the Atlantic Ocean is 
known as the Sargasso Sea on ac- 
count of the Sargassum floating 
there. The Fucales have no asex- 
ual method of reproduction but 
reproduce sexually by the fertili- 
zation of eggs by spermatozoids. 
The odgonia and antheridia are 
borne in flask-shaped depressions 
called conceptacles (Fig. 353). 
CLASS RHODOPHYCEAE 
(RED ALG) 
The Lhodophyceae are usually 
red or violet or sometimes dark 
purple or reddish brown. The color 
is due to a red pigment, phyco- 
erythrin, which masks the chloro- 
phyll. The red alge are mostly 
marine forms and include the majority of seaweeds. They are 
frequently abundant along the coasts and are often objects of 
great beauty. The Rhodophyceae, like the Phaeophyceae and the 
