42 BRITISH SEA-WEEDS. 



At present it contains only about a, dozen species, which 

 are all found in the northern latitudes of the Atlantic 

 Ocean, either on the coasts of Europe or America, most 

 of them being common to both continents. They grow 

 in? -large- numbers' 'on "rocks between the tide-marks, 

 where their 'tough leathery texture • and large size fit 

 them to bear exposure to air and sun, and to afford 

 shelter to more delicate species. ..... 



Fucus vesiculosa. Twin-bladder Wrack. 



Frond flat, with a distinct midrib, not cut at the edges, 

 varying in length from a few inches to two feet, or more. 

 Air-vessels, when present, globular, generally in pairs, one 

 on ?£c1P^5rde s oi trie midrib. Spore-receptacles terminal, 

 variable in" shape, r sometimes' 'forked, 5 full of mucus. 



This is, perhaps, the most common British Sea-weed. 

 It is abundant on all parts of our coasts^ and is sometimes 

 used as fodder for cattle, "and more frequently as manure. 

 It was formerly employed very largely, in combination 

 with other species', in the manufacture of kelp, for the 

 use of the glass-blowers and sOap-boilers. In those 

 days, a piece of rocky coast suitable for the growth, 

 or, I might almost' say cultivation,* of Sea-weed was 

 a valuable property ; but improvements in the manu- 

 facture of alkalies have destroyed the trade of the 

 kelp-maker, and with j£, the value of the rocky shore 

 where it was conducted. 



Fucus ceratnbides. Morn Wrack. 



^rohd'flat, with a midrib, not ,cut at the edges, about a 



foot long ; main branches twice as wide as the branchlets 

 >r . r , j r< ..£y „• : • i ft 3 i : J .',.- .'''"'. 



springing from them, which are more distinctly forked. Air- 

 vessels "altogether absent. Spore-receptacles at the tips of 

 the branchlets, small, spindle-shaped, sometimes forked. 



