337 



weed reported by navigators to be from 500 to 1 500 feet in length : the leaves 

 are long and narrow, and at the base of each is placed a vesicle filled with 

 air, without which it would be impossible for the plant to support its enormous 

 length in the water ; the stem not being thicker than the finger, and the up- 

 per branches as slender as common packthread." 



These remarks may be concluded by a reference to the following works, in 

 which certain information relating to the animal nature of certain Confervae 

 may be found : Nees von Esenbeck Die Algen des Sussen Wassers (1815); 

 Treviranus in Ann. des Sc. 10. 22.(1817): Gruithuisen in Nov. Act. Jicad. 

 Leopold. Curios. 10.437.; Carus in the same, 11, 491. (1823); Gaillon in 

 Ann. Sc. Nat. 1. 309. (1823); Desmazieres in the same, 10. 42. (1825), 

 and 14. 206, (1828) ; Unger in the same, 13. 431. (1828) : all of which should 

 be carefully consulted by those who wish to form any accurate judgment upon 

 this most curious and interesting subject. 



Geography. This has been treated upon carefully by Lamouroux in the 

 Annates des Sciences Naturelles, vol. 7, and by Dr. Greville, in the Alga, Bri- 

 tannicoz. Algoe are most important in the economy of nature for forming the 

 commencement of soil by their deposit and decomposition. The basin of the 

 ocean is said to be continually rising by the deposit of such plants, particularly 

 of Conferva chthonoplastes, the closely aggregated slimy fibres of which form 

 dense beds. Ed. P. J. 2. 392. The same circumstance occurs in lakes and 

 ditches : the bottoms of some of the former, in this country, are no doubt in- 

 creased by the curious production called Conf. regagropila. To the peculiar 

 distribution of Phamogamous plants into certain botanical regions, a fact familiar 

 to all botanists, there is something analogous in the submersed Flora of the 

 ocean. We find latitude, depth, currents, influencing the forms of Algae in nearly 

 the same way as latitude, elevation, and station, affect those plants which are more 

 perfect ; and as many of the latter are confined to small extent of country, so 

 do several of the Algae extend but to short distances in the sea. Thus Odon- 

 thalia dentata and Rhodomela cristata are confined to the northern parts of 

 Great Britain, while many others are peculiar to the southern parts ; and, on 

 the contrary, many are cosmopolites of an unbounded range, such as Codium 

 and Ulvaceae. The latter thrive best in the polar and temperate zones, Dic- 

 tyoteaj increase as we approach the equator, Fuci particularly flourish between 

 the parallels of 55° and 44°, and, according to Lamouroux, rarely approach 

 the equator nearer than 36°. The articulated or imperfectly formed fresh- 

 water Algaa are nearly confined to the temperate and northern parts of the 

 world, being almost unknown or undescribed from within the tropics. The 

 number of species is scarcely capable of being eslimated. 



Properties. For what wise purpose the Creator has filled the sea and the 

 rivers with countless myriads of these plants, so that the Flora of the deep 

 waters is as extensive as that of dry land, we can only conjecture ; the uses to 

 which they are applied by man are, doubtless, of but secondary consideration ; 

 and yet they are of no little importance in the manufactures and domestic 

 economy of the human race. Dr. Greville describes them thus (Algoz Bri- 

 tannics, xix.) : 



" Rhodomela palmata, the dulse of the Scots, dillesk of the Irish, and sac- 

 charine Fucus of the Icelanders, is consumed in considerable quantities 

 throughout the maritime countries of the north of Europe, and in the Grecian 

 Archipelago ; Iridcea edulis is still occasionally used, both in Scotland, and the 

 southwest of England. Porphyra lachriata and vulgaris is stewed, and brought 

 to our tables as a luxury under the name of Laver ; and even the Ulva latissima, 

 or green Laver, is not slighted in the absence of the Porphyra;. Enter omor- 

 pha compressa, a common species on our shores, is regarded, according to Gau- 

 dichaud, as an esculent by the Sandwich Islanders. Laurentia pinna tifida, 



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