174 
SEA-WEEDS. 
600 feet wide. These bands must os¬ 
cillate with the tides between two corres¬ 
ponding zones of rest, one at the turn of 
the flood, and the other at the turn of the 
ebb. It is doubtful whether the Fucus 
natans or Sargassum bacciferum grows on 
rocks at the bottom of the Atlantic, between 
the parallels of 40° north and south of the 
equator, and, when detached, is drifted 
uniformly to particular spots which never 
vary, or whether it is propagated and grows 
in the water ; but the mass of that plant, 
west of the Azores, occupies an* area equal 
to that of France, and has not changed its 
place since the time of Columbus. Fields 
of the same kind cover the sea at the 
Bahama Islands, and other places, and two 
new species of it were discovered in the 
Antarctic seas. 
“ The Macrocystis pyrifera and tlie Lam¬ 
inaria radiata are the most remarkable of 
marine plants for their gigantic size and the 
extent of their range. They were met with 
on the Antarctic coasts two degrees nearer 
the south pole than any other vegetable pro¬ 
duction, forming, with one remarkable 
