FUCUS VESICULOSUS. BLADDER FUCUS. BLADDER-WRACK. 
Class XXIV. CRYPTOGAMIA.— Order III. ALGJL 
Natural Order, ALGJE. THE SEA-WEED TRIBE. 
Fig. («) part of the outside of a receptacle magnified; (6) horizontal section of a receptacle; (c) tubercle; (<f) spores; (e) contents of a 
spore; (/) some of the same; (9) longitudinal section of a vesicle. 
Under the term Fuci are comprehended a tribe of plants, commonly included with the Ulvse and marine 
Confervse, under the more general tide of submerged Algae, or Thalassiophyta, and well known in this 
country by the popular name of Sea- weeds. In Scotland the name Wrack, (probably from the French 
varec ,) is often applied to those fuci, which are cut on the shores for the manufacture of kelp. 
The economical uses of sea-weeds are numerous and important. To the agriculturist they furnish a 
valuable manure. To the glass-maker and soap-boiler they yield the fixed alkali, and the manufacture of 
kelp for this purpose became a valuable source of revenue to the proprietors of the rocky shores of Europe, 
particularly of Britain, and more especially of those of the Northern and Western Islands of Scotland, 
during the late war. From the ashes of the fuci the chemist has derived the very curious elementary sub- 
stance named Iodine. Several of them are so rich in saccharine matter and vegetable mucilage, that on the 
shores of the northern countries of Europe, and the Scottish islands, much of the winter provender of cattle 
is derived from them. A few of them also afford food to man; some of the smaller sorts are used as con- 
diments; while others are employed as medicines. 
The Fucus vesiculosus is a perennial plant, growing everywhere on the British shores, on rocks and 
stones, or cast upon the beach ; bearing its fructification in the spring. The root is an expanded, black, 
woody, callous disc. The frond is smooth and glossy, flat, winged, from one to four feet long, and from 
\ in. to If in. wide, linear, forked near the root, and afterwards repeatedly dichotomous, of a dark 
olive-green colour, becoming paler near the apices, and when dry black and dull. All the branches are 
nearly of equal height, with the apices rounded, and not unfrequently notched; the margins entire. The 
substance of the frond is coriaceous, flexible and tough, but brittle after it is dried ; and through its whole 
length furnished with a midrib of a blackish colour, and as thick as a goose-quill, but gradually growing 
pale and thin. In the membranous part of the frond throughout its whole length are found immersed 
spherical vesicles, varying in size from a pea to a hazel-nut, externally smooth, and containing in their 
cavity a quantity of air. Besides these, particularly in the spring, almost always near the apices, are often 
observable elliptical swellings of a pale yellowish green colour, an inch or two in length, and sometimes 
occupying the midrib, so that the whole becomes inflated and nearly cylindrical. The fructification con- 
sists of compressed, turgid receptacles, solitary or twin, placed at the ends of the branches, varying in form, 
but mostly elliptical, from one-fourth of an inch to two inches long, and perforated with very minute pores, 
under which lie imbedded spherical tubercles, composed of short jointed fibres, mixed with seeds of an 
elliptical form, surrounded with a pellucid limbus, and appearing under a powerful microscope to contain 
six or seven roundish grains: the centre of the receptacle is filled with a colourless and tasteless mucus, 
through which passes a network of anastomosing fibres. The varieties a. /3. y. and S. are found upon the 
shores of the British isles, and of all the north of Europe, plentifully. 
In Scotland this is sometimes called Black Tang; sometimes Kelp-ware, and when the receptacles are 
large and swollen, Strawberry-ware. The Norwegians call it Kue-tang. It is the Quercus marina or Sea 
Oak of the older writers. 
Qualities and Chemical Properties. — The most important uses to which Fucus vesiculosus is 
applied is in the manufacture of Kelp, which is a very impure carbonate of soda, containing sulphate and 
chloride of sodium, with a portion of charcoal; and is manufactured in Scotland chiefly in the months of 
July and August. 
Its medical virtues have been much celebrated by Dr. Russell in his Dissertation concerning the uses 
of Sea-water in the Diseases of the Glands. He found the saponaceous liquor or mucus in the vesicles of 
the plant to be an excellent resolvent, and useful in dispersing scrofulous swellings. He recommends the 
patient to rub the tumour with these vesicles bruised in the hand, and afterwards to wash the part with sea- 
water. 
Iodine, as already hinted, is also yielded by kelp. Its name being derived from violaceus, in 
allusion to the very striking circumstance of its yielding a violet-coloured gas on being exposed to an in- 
crease of temperature. It was first discovered accidentally by M. Courtois, of Paris, and its properties have 
been since accurately examined by Clement and Desormes, Gay Lussac, Sir II. Davy, Vauquelin, and Wol- 
