FRESH-WATER ALG. 241 
the very early or embryonic condition of the more 
complicated structures. 
The Mostoc (Fig. 22), one of the species belong- 
ing to this strange class of plants, is interesting on 
account of the historical associations connected 
with it. It occurs in the form of a greenish jelly 
or slimy mass on gravelly soils, rocks, pastures, 
and roadsides, among grass and moss, especially 
in moist weather. It is widely distributed, occur- 
ring as far south as the Antarctic regions, several 
species having been found by Dr. Hooker on wet 
Fic. 22.—NostToc COMMUNE. 
rocks near the sea in Kerguelen’s Land. It 
ranges, on the other hand, as far north as Baffin’s 
Bay, and the shores of the Polar Ocean, growing 
on the soft, boggy slopes of the sea-shore, from 
whence it is drifted about by the wind in detached 
masses, and forming the only vegetable produc- 
tion of any importance over many square leagues. 
Dr. Sutherland, in his fascinating journal, relates 
that it has often been found in great abundance 
on floating icebergs, and in small depressions in 
Q 
