TAXONOMY 
I 93 
is many-celled. These tufts are found on eelgrass or other algae 
as well as attached to pilings of wharves in salt water. It is a 
striking illustration of the simplest form of brown algae and 
serves to show the beginning of a more complex form of repro- 
duction than that observed in 
the forms studied up to this 
time. On examination of a 
filament we find it to consist 
of many cells joined end to 
end. A single cell has a cell 
wall of cellulose, just within 
the cell wall there is a layer 
of protoplasm. Going toward 
the center we find an irregular 
chromatophore containing a 
brown pigment called phyco- 
phaein. From certain cells of 
the filament spherical sporangia 
(spore cases) arise, which are 
unicellular. They contain 
numerous biciliate zoospores , 
which escape into the sea 
water, move about and later 
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 cham- 
bers have resulted, which are 
called plnrilocular sporangia. 
Each cell of a plurilocular 
sporangium contains a gamete or sexual cell, which resembles 
in many details a zoospore. When the sporangium matures 
these gametes are discharged into the salt water. They fuse 
together in pairs and form zygospores. Each zygospore under- 
13 
Pig. 78. — End of large branch of 
Fucus vesiculosus (natural size); e, re- 
ceptacle; b, air bladder. . 
