INTRODUCTION TO CRYPTOGAMIC BOTANY. 219 



expansion of the top of the stem, or which is simply cylindrical, 

 the former consists of species which inhabit the southern seas 

 and tropical regions, while those belonging to the latter are 

 eminently plants of northern latitudes, their maximum being 

 attained on the coasts of North America. On our own coasts 

 the Laminarice, which are all inhabitants of tracts exposed 

 only at low tides, compose, perhaps, in point of mass and 

 volume, the larger part of our Algae, even including the Fuel 

 Individuals of L. bulbosa occur, which are a sufficient load 

 for a man. On our own coast they attain many feet in length. 

 In the other division, however, the length is sometimes 

 counted by hundreds of feet. Indeed, from the mode of forma- 

 tion there is no Hmit, except such as may be placed in the 

 natural decay of the older portions. 



203. But, perhaps, the genus Nereocystis is the most won- 

 derful of all, whose stem occasionally attains a length of 300 

 feet, though extremely slender even at the top, where it is 

 surmounted by an enormous floating bladder six or seven feet 

 long, affording a favourite resting-place to the sea otter. The 

 account, indeed, is apparently so fabulous as given by Mertens, 

 in an interesting paper on the botany of the Russian possessions 

 in America, that it could not be believed did it not depend upon 

 unquestionable authority. The filiform stem, which is about as 

 thick as packthread, when two or three feet long, swells suddenly 

 above into a globose bladder. From the top of this springs a 

 tuft of geminate leaves, mostly rising on five petioles. These 

 leaves are lanceolate and membranaceous, from one to two feet 

 long, and two inches broad in the centre. As the plant grows 

 older, the stem increases enormously in length, but only slightly 

 in thickness. The globose bladder swells into a turnip-shaped 

 or retort-like cylinder, six feet long, and four feet six inches 

 or more in diameter in the widest part, the lower extremity 

 gradually passing into the stem. The leaves, which at first 

 were marked with a few faint nerves, split in their direction, and 

 cover a large space by their entangled mass, and attain a length 

 of twenty-seven feet or more. Where the plant grows in any 

 quantity, the surface of the sea becomes impassable to boats, 

 in consequence of the dense floating masses of vegetation. The 



