IV. FUCACEJ5. 53 



The FucacecB are rarely deep-water plants. One species (F. canallculatus), com- 

 mon in Europe, begins to grow at the extremity of high water mark, in places 

 where it is exposed to the atmosphere during the greater part of the twenty-four 

 hours, and only submerged by the highest tide waves. In such places, though its 

 growth is dwarfish, it frequently produces fruit. As it descends in depth toward 

 mid-tide level, the frond becomes larger and more luxuriant, and in the space 

 between this limit and that of quarter-tide, the greater number of individual 

 plants occur. Few straggle into deeper water. This species, of all others, is best 

 fitted to resist drought, its fronds being peculiarly dense and leathery ; and in a 

 warm day it frequently becomes crisp and dry, and to all appearance baked to 

 death, during the recess of the water ; and yet, on the return of the tide, the 

 withered fronds expand and become flexible and juicy. Perhaps the non-occur- 

 rence of this plant on the American coasts may be owing to the fiercer heats which 

 it would be subjected to, in the exposed places that it would naturally occupy. 



With the slight exception of this semi-aerial species, all the ordinary Fucaceaj 

 are characteristic of the space strictly defined by the tide marks, extending 

 through the whole range of exposed rock ; over which in temperate latitudes they 

 usually spread so densely, that the colour of the sea-shore is as clearly character- 

 ised by them, as is the colour of the ground by the species of grasses which con- 

 stitute its green mantle. 



A few of the most highly developed genera (Cystoseira, Sargassutn, ^-c.) are pro- 

 ductions of deeper water, commencing to grow at depths at which the Fuel cease, 

 and extending into a zone of depth ■where they are constantly submerged. I am 

 not aware that*any species has been traced into a deeper zone than that occupied 

 by Laminarice. 



One remarkable species of the genus Sargassum has long been famous by the 

 name of Gidficeed or Sargazo (sea-lentils)^ under which most voyagers since the 

 days of Columbus have spoken of it. That great discoverer was the first to 

 encounter it in modern times, (16th September, 1492) and with his account we are 

 therefoi'e most familiar ; but possibly the weedy sea which Aristotle sj)eaks of as 

 having been met with by the Phoenicians, at the .termination of their voyage, may 

 have been an early discovery of the same bank. It is curious that the great bank 

 which extends between the 20th and 45th parallels of north latitude, and in 

 40° W. from Greenwich, appears to occupy the same position at the present day as 

 it did in the days of Columbus. Between this bank and the American shores, 

 various smaller strata and detached masses of seaweed occur, being throAvn into 

 this portion of the ocean by the eddy caused by the sub-circular motion of the 

 great oceanic currents. The whole of this immense space of ocean, which is re- 

 ported to be thickly covered with seaweed, is computed by Humboldt at upwards 

 of 260,000 square miles, an area almost six times as large as Germany ;* but it is 

 not to be supposed that all this space is equally clothed with floating verdure. In 

 many places the weed occurs in distant and narrow ridges, leaving spaces of clear 

 water between. This portion of the Atlantic seems to be the chief settlement of the 



* Jolinst. Pliys. Atlas. Atlantic, p. 5. 



