THE PLANTS OF THE SEA. 49 
little protuberance shows itself, which continues to elongate, and at 
last is converted into a transparent filament, containing no green 
matter, and only enclosing some yellowish grains at its extremity. 
Soon many of these roots are formed at the base of the spore, and 
by these the young frond is fixed (figs. 7, 8,9, 10). In this the 
cells are multiplied by partitions, dividing those which already 
exist ; little by little it lengthens and expands to a pear-like shape, 
and of a brown colour. The young frond is presently formed. It 
already shows, very slightly, it is true, the main features of the 
parent plant. Some day or other it will reach its full development, 
and in its turn propagate individuals of its species. 
BLADDER WRACK. 
(Fucus vesiculosus.) 
Every storm casts up upon the shores of eastern Europe vast 
heaps of wrack and other sea-weeds. These are collected, and 
carried inland to serve as manure. The poor people dry it for 
their fuel. Formerly from these marine plants soda was prepared. 
These sea-weeds cover the shore and submerged rocks. They 
form upon the sand a line showing the height to which the waves 
wash. The principal of them are the knobbed wrack (Fucus 
nodusus), which floats out upon the water, buoyed up by large 
air vessels placed singly in the stem; the bladder wrack ( Fucus 
vesiculosus), which is known by its air vessels, which are as large 
E 
