name Agar-Agar, is largely consumed in China, both as an article of food, and as yielding a very strong glue. The jelly prepared from it is certainly superior to that yielded by our Chondrus. A Swan River species (Gigartina speciosa, Sond.) affords a gelatine of perhaps equal value. Both these might be obtained in abundance, should a demand for them arise. These few instances, selected out of a multitude, show that the Algæ are not undeserving the notice of the economist, especially in a country where the constant increase of population renders desirable every effort to increase the supply of food. That the vast stores of Carrigeen which our coasts afford, have been wholly neglected during the recent famine, is the result partly of ignorance, and partly of the invariable companion of ignorance, -prejudice.

The only other Rhodosperms which I shall notice are the very curious tribe of Corallineæ,-the jointed Corallines of Linnæus,-plants which have been regarded, almost universally since the time of Ellis, as members of the animal kingdom. This tribe is most numerous in species as we approach the tropics, and the British examples are not many; but one of them, Corallina officinalis, is so common on all our coasts, that it must have attracted the notice of every one who has paid any attention to marine productions, and it will serve as a type of the family. It will at once be seen that this plant differs from other sea-weeds in being of a calcareous nature, effervescing when thrown into an acid solution; and in this respect it resembles a true coral. It neither produces Polypes, however, nor exhibits any animal character,

while it yields spores, contained in receptacles perfectly

CORALLINA OFFICINALIS.

analogous to those of the Algae of the red series, to which its colour also allies it. These spores were observed and figured by Ellis; and it is therefore the more strange that the vegetable nature of the family has not been earlier acknowledged. Corallina officinalis generally occurs in society, covering the bottoms of shallow tide

pools with its jointed fronds, which afford a welcome resting-place to many of the smaller Algæ and to marine animals. It always springs from a broad, calcareous base, often of considerable thickness, which incrusts the surface of the rock. It commences to vegetate, though feebly, immediately within the limit of highwater, and extends throughout the whole littoral zone, gradually acquiring fuller developement as the water deepens; and the best specimens are always to be found nearest to low-water-mark. It is occasionally dredged from the depth of three or four fathoms, or perhaps more; but specimens from water of that depth are less perfect than those collected about low-water-mark, clearly showing that, at that level, the species is in the situation best adapted to its nature. The species of the genus Corallina are very imperfectly known, and many supposed species may ultimately prove to be merely varieties of this common and very generally diffused

plant, which in some form or other inhabits the shores of most temperate latitudes.

Along with Corallina officinalis, and also creeping among the roots of various other Algæ, may often be seen the fronds of a lichenoid species of calcareous plant, Melobesia (or Nullipora) lichenoides, affixed to the surface of the rocky soil. This is of the same family as the Corallina, but simpler in structure. By some authors it is supposed to be merely the imperfectly developed state of a Coralline; but the evidence for this opinion. does not appear satisfactory, and in the imperfect state of our knowledge it is better to consider these plants distinct. In appearance they are widely different, though similar in microscopic structure and substance. The Melobesia belongs to a group of the family, characteristic of a deeper water, and which we shall have occasion to speak of in our chapter on Dredging.

The very imperfect outline which I have just given of the several groups of marine plants, is all that the plan of this little volume admits of, without trenching too much on subjects of perhaps more general interest. The great elegance of many of the sea-weeds, and the ease. with which specimens may be preserved, retaining much of their original beauty, attract many persons who occasionally visit the sea-shore; and sea-weeds are collected either as objects of scientific interest, or for the manufacture of pictures for albums or screens. Those who collect sea-weeds for the latter purposes, in general care little to know their history; but perhaps when some of its facts are known, they may be regarded as not without interest. I have, therefore, mentioned

110

SEA-WEED PICTURES.

some of the principles on which the classification of these plants is based, and described some of the commoner species of our shores. For a more detailed history of the family, I must refer my readers to books more expressly written on the subject.*

* See the Author's "Phycologia Britannica," containing coloured plates and detailed descriptions of all the British Sea-weeds: also, his "Manual of the British Marine Algæ," 2nd edit., with 27 plates of genera (in preparation).

IN the vegetation of the sea, Nature has provided both shelter and food for an infinitude of animals. Were we to speak of the uses of sea-weeds, and confine ourselves to their adaptation to the wants of man, we should much misinterpret the office which this portion of the vegetable world discharges in the general economy. However great their uses to man, these are absolutely insignificant in comparison to those benefits for which the lower tribes of animated nature are indebted to the sea-weeds. Troop after troop of animals, one more highly organized than another, either derives its nourishment from the sea-weed itself, or uses the submarine forest as a hunting-ground, where it fulfils the