BOTANY. 81 
from which the group takes its name, is the green plant 
which usually adorns marine aquaria. It is composed of 
layers of cells bound together, and its reproduction is 
effected by zoospores, such as we noticed in Pediastrum. 
FUCOIDZE. 
The brown or olive-colored Algae, or Fucoidz, differ not 
only in their color from the green A 
ex, of which we have 
just spoken, but equally as regards their size and manner 
of reproduction. They are confined to the sea, and are 
found generally on submarine rocks, which are exposed, 
however, at low tide, to heat, light, and atmospheric influ- 
ences. This seems to be necessary for the healthy growth 
of the brown Alga, since the specimens that are brought 
up from greater depths do not exhibit so hardy a structure 
as those that live at the surface. The Fucoide are com- 
monly known as sea-wrack; but that generally picked up 
at the sea-shore gives no idea of the immense size which 
some of the brown Algae attain, the Macrocystis of the 
Californian coasts reaching a length of four hundred feet. 
Among the Fucoidz are included the Laminaria, or leath- 
ery sea-weed; the Fucus (Fig. 99), or bladder-wrack, so 
called from floating on the surface of the sea by means of 
air-bladders. This bladder-like arrangement in the Sargas- 
sum, or gulf-weed, takes the form of a bunch of berries, 
and is the most characteristic feature of the plant. The 
importance of the brown Algz may be estimated from the 
fact that forty thousand square miles of the Atlantic Ocean 
are covered with a kind of oceanic forest of Sargassum. 
(Fig. 100.) The presence of this plant gave Columbus 
vain hopes of being near land. The reproduction of the 
brown Alge has not as yet been perfectly made out. It 
is known, however, that the process is sometimes carried 
on by zoospores, as in Pediastrum, or by the intervention 
6 
