Algals.] 



FUCACE^. 



21 



Fig. IX. 



activity." Such bodies are regarded as analogous to the spii-al threads of mosses and 

 other cryptogamic plants. Indeed, according to ]\1. Thuret, such threads are also fur- 

 nished \vith ciliary locomotive organs. But what proof is there that these cui-ious 

 bodies are pollen i 



One of the most remarkable plants of the order is the Hydrogastrum, which Endh- 

 cher describes as a perfect plant, with root, stem, bud, and fruit, in imitation of the 



most highly developed races, hut all produced by 



^ the branching of one single cell. 



Professor MoiTen thinks that he has ascertauied 

 that the animalcule called Rotifer vulgaris, is 

 actually genei'ated in the cells of Vaucheria cla- 

 vata. He Hves in certam protuberances formed on 

 the stem of that plant, travels quite at his ease 

 within them, traverses the partitions, displaces 

 the colouring matter. {Ann. Nat. Hist. vi. 346.) 

 Like all this alhance the Seawracks have no 

 particular geographical hmits, but occur wherever 

 the ocean or rivers spread themselves over the 

 land. They are, however, remarkable for the enor- 

 mous space which single species of them occasion- 

 ally occupy ; some of them forming subaqueous 

 forests in the ocean, emulating in theu- gigantic 

 dimensions the boundless element that enfolds 

 them. Scytosiphon filum, a species common in 

 the North Sea, is frequently found of the length 

 of 30 or 40 feet ; in Scalpa Bay, in Orkney, 

 according to Mr. Neill,this species forms meadows, 

 through which a pinnace with difficulty forces its 

 way. Lessonia fuscescens is described by Bory de St. Vincent as "25 or 30 feet in 

 length, with a trunk often as thick as a man's thigh. But all these, and indeed every 

 other vegetable production, is exceeded in size by the prodigious fronds of Macrocys- 

 tis pyrifera. " This appears to be the sea-weed reported by na\ngators to be from 500 

 to 1500 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 upper branches as slender as common packthread." This plant, and Durvillsea 

 utihs, was seen by Dr. Joseph Hooker in lat. 61" S. in large vegetating patches, where- 

 ever the water was free of icebergs ; and Scytothaha Jacquinotii as low as 63° S. 



Some of the species are eatable, owing doubtless to the large quantity of gelatinous 

 matter that they secrete. The young stalks of Laminaria digitata and saccharina are 

 eaten under the' name of " tangle." In Asia, Sargassum acanthocarpum and pyriforme, 

 with Laminaria bracteata, and in the Sandwich Islands, Sargassum cuneifolium, are also 

 used for food. A^'hen stripped of the tliin part, the beautiful Alaria esculenta forms a 

 part of the simple fare of the poorer classes of Ireland, Scotland, Iceland, Denmark, 

 and the Faroe Islands. The large Laminaria potatorum of Austi-alia furnishes the 

 aborigines with a proportion of their ' instiniments, vessels, and food.' On the authority 

 of Bory de St. Vincent, the Durvillsea utihs and other Laminaridee constitute an equally 

 important resource to the poor on the west coast of South America. In some of the 

 Scottish islands, horses, cattle, and sheep, feed chiefly upon Fucus vesiculosus dming 

 the winter months ; and in Gothland it is commonly given to pigs. Fucus serratus 

 also, and Scytosiphon filum, constitute a part of the fodder upon which cattle are sup- 

 ported in Norway. In the manufacture of kelp, for the use of the glass-maker and 

 soap-boiler, Seawracks take their place among the more useful vegetables. The species 

 most valued for this purpose are, Fucus vesiculosus, nodosus, and serratus, Laminaria 

 digitata and bulbosa, Himanthaha lorea, and Scytosiphon filum. It is principally, 

 indeed, because of the quantity of soda which they contain that they are ibund so useful 

 as manures. In medicine they have been occasionally employed, as, for instance, Fucus 

 vesiculosus in Europe agamst scrofula, Sargassum vulgare in Portuguese India against 

 calculus, and Sarg. bacciferum with some Laminarias in South America against tumours 

 and strangury. But whatever medical value they possess seems to be owing to the 

 presence of Iodine, which may be obtained either from the plants themselves, or from 

 kelp. French kelp, according to Sir Humphry Davy, yields more Iodine than 

 British ; and, from f-jome experiments made at the Cape of Good Hope, Ecklonia buc- 

 cinalis is found to contain more than any European sea-weed. Iodine is known to be a, 



Fig. IX. Hydrogastmm, (Endlich. prundz, p. .54, f. 47.) 



