CERAMIACEiE. 



673 



The Sea-weeds are valuable as furnishing large quantities of Kelp or Soda, 

 as being the source from which Iodine is procured, and also as affording 

 wholesome food. The ashes of the whole of the species contain Soda and 

 more or less Iodine, and it is to the presence of these two bodies, that the 

 Fuci owe their medicinal properties in scrofula and glandular swellings. 



Iodine is extracted from the mother liquor of Kelp, made from a variety of 

 maritime plants, but principally from those of this order and the next. 

 Among these, the species of Rhodomenia and Laminaria afford the most. 

 (See Pereira, Elem. Mat. Med. i. 230.) But much is obtained from several 

 species of Fuci. 



Among the edible species may be mentioned Alaria esculenta, extensively 

 used as food in Ireland, Scotland, Iceland, &c, as are also the young stalks 

 of Laminaria digitata and L. saccharina ; these are called Tangle. In 

 Asia, Sargassum acanthocarpum and pyriforme, with Laminaria bracteata, 

 and, in the Sandwich Islands, Sargassum cuneifolium, are in like manner 

 used for food. But the largest proportion of the nutritious sea-weeds belong 

 to the next order. 



Order 123.— CERAMIACEtE.— Lindley. 



Sea-weeds, usually of a rose or purplish colour. Cells long and tubular, or round and 

 short, or polygonal, sometimes arranged in a single row ; sometimes disposed in several 

 parallel rows, forming an articulated frond, or if unequal lengths, forming a cellular 

 frond. Their propagation is by spores (sphaerospores and tetraspores) collected in fours 

 or threes within a transparent perispore, in bodies of different forms and structure. 



Fig. 325. 



a. Rhodomenia palmata. b. R. ciliata. c. Laminaria saccharina. d. Iridsea edulis. e. Alaria 

 esculenta. /. Ulva latissima. 



The species of this order, like the last, are found in all parts of the world, 

 but are most frequent between 35° and 40° N. Lat., and are comparatively rare in 

 the southern hemisphere. They are mostly very gelatinous, and hence are valu- 

 able as food. One of them, Chondrus crispus, or Carrageen, has been recog- 

 nised as officinal, though it does not appear to be superior in its demulcent or 

 nutritive qualities to several others of the order. From an analysis of it by 

 Herberger, it is shown to contain large quantities of a peculiar vegetable 



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