MARINE BOTANY. 113 



and animals possess such a flexible nature, as to accomodate 

 itself to the most varying climates. 



The group of the olive-coloured sea-weed plays, however, 

 a far more important part in the Ocean household. To it 

 belong both the species which, on the fall of the tide, give 

 our rocky shores their peculiar gloomy colour, and the 

 mighty Laininarise (oar- weed), which, wherever they find a 

 firm soil, form a submarine forest-belt round the coasts to a 

 depth of several fathoms. 



The small Fucus canaliculatus, whose small channeled 

 stems and branches have no air-vessels, first makes its 

 appearance on our leaving the land ; it is followed by the 

 Fucus nodosus, a large species, with powerful-looking stalks 

 distending at some places into air-vessels ; and by the Fucus 

 vesiculosus, a gregarious plant, which covers the rocks far 

 and wide, from one to two feet above high-water mark down 

 to the verge of the lowest tide. Through the broad forked 

 leaves runs a wide rib, which is ornamented on each side 

 with numerous air-vessels found in pairs. The deepest spot 

 in the littoral zone, or belt of rock, extending between ebb 

 and flood, is occupied by the equally gregarious Fucus 

 serratus, which is distinguished by its toothed margin leaves 

 and absence of air-vessels. 



These species of Fucus are very frequently found on the 

 flat rocky west coast of Scotland and Ireland, as well as in 

 Brittany, where enormous quantities were formerly burnt, 

 and sold for the production of soda under the name of kelp 

 or varech. At the Orkneys alone 20,000 men were engaged 

 the entire summer in collecting and burning it. Now it is 

 no longer employed for this purpose ; as, to the great injury 

 of the needy inhabitants of those coasts, soda is obtained mpre 

 cheaply from salt ; still they are employed in collecting 

 iodine, which, of course, has not nearly such commercial 

 value. It is also greatly used for manuring fields, some 

 being reduced to ashes, some in a mouldering state. Thus 



