With the exception of the Fuci or common rock-weeds, I never place seaweeds in fresh water: with these, especially Fucus serratus, F. nodosus, F. vesiculosus, and F. canaliculatus, a few hours' immersion in fresh water is an advantage, as it soaks the salt out of their fronds and renders them more pliable. As all the Fuci turn black in drying, and few of them adhere well to paper, I arrange my specimens in single layers between the folds of a clean dry towel, and keep them under pressure until they are quite dry; they may then be put away loosely, or gummed on sheets of paper.
The foregoing directions for mounting filamentous seaweeds are applicable to all the branching species of Olive, Red, and Green plants; but in each of the three subdivisions there are a few species which are so gelatinous—in fact, so soft and spongy, that they require the utmost care during pressure, otherwise they adhere to the calico and break off in fragments as it is drawn away. Such plants must be left to dry in a horizontal position for an hour or so before the calico and blotters are placed over them, and pressure must be very slight until they have adhered closely to the paper. Among the Chlorosperms, or green plants, there are the various species of Codium, young plants of which only are manageable or indeed desirable. In the Melanosperms, some species of the genus Mesogloia will require care and patience in mounting, as well as the long string-like plant, known as Chorda filum; and again, the spreading tuberous mass called Leathsia tuberiformis, portions of which should be cut from the rock, the sand scraped and washed out, then laid on the wet paper, and allowed to shrink for some hours ere calico blotters and pressure be applied. These difficulties are much more numerous among the Rhodosperms, or red seaweeds, experience only teaching the best method of treatment. I will, however, mention the names of some very troublesome plants, the fronds of which, if subjected to pressure too soon, burst and discharge their carmine contents; not only presenting an unsightly appearance, but destroying the specimen. These are Griffithsia corallina, Dudresnaia coccinea, Naccaria Wigghii, all the Chylocladia, and the rare Gloiosiphonia, as well as the slimy worm-like plant known as Nemalion multifidum.
In addition to these troubles among the red plants, there is an opposite difficulty connected with several Rhodosperms which must be pointed out; and that is owing to an absence or scarcity of gelatine in their substance, which is in some of a stout, leathery, or horny nature, and in others is due to a coating of carbonate of lime, which completely envelops the vegetable structure. Among the former may be mentioned the several species of Phyllophora, and several among the genera Gigartina, Chondrus, and Sphærococcus; and in the latter, all the calcareous Algæ, especially the well-known Corallina officinalis and Jania rubens. All these, and several others of a membraneous nature, among the olive as well as the red weeds, must be first mounted in the ordinary manner, and when they are tolerably dry and begin to shrink away from the paper, fill the mounting-dish with stale skimmed milk; refloat the plants on their papers in the milk, and indeed go through the same process as before with the sea-water, but be careful to absorb all the milk from off the surface of the plants and the back of the papers, and then, after the usual time for drying and pressing, the most obstinate seaweed will be found adhering perfectly to the paper, and will remain so permanently.
One more difficulty must be referred to for the benefit of young beginners, who, in mounting some of the Laminaria and that peculiar olive weed called Himanthalia lorea, may wish to preserve the thick-branching roots and stems. First wash the roots as clean as possible, and then, with a sharp penknife, make a clean cutting horizontally of the whole root and some little distance up the thick round stem; then, after having removed the cut portions, place the inner surface of the root and stem on the paper, and the gelatinous matter which oozes from the plant will cause the roots to adhere firmly to the paper, and in drying, the usual olive tint of the various species of Laminaria will be finely preserved. Some botanists employ a mixture made of isinglass, dissolved in alcohol, to fix some of the horny or robust species on paper; but if gum be made use of, it is better to employ gum tragacanth than gum-arabic, because, in drying, the former has none of that objectionable glare which is peculiar to gum arabic.
As regards the best method of pressing seaweeds, I think I can hardly do better than refer my readers to the figure of a Seaweed Press ([Fig. 45]), which I invented for myself many years ago, in which I have pressed many thousands of beautiful seaweeds. Almost any degree of pressure can be obtained in it: first, by the thumb-screws on the iron rods at each corner, and, finally, by means of the clamp which is strapped on the top of the press. Any intelligent cabinet-maker or ironmonger could provide such a press from an inspection of the figure; the cost, of course, varying with the dimensions and the number of boards.
Fig. 45. Seaweed Press.
With respect to localities favourable to seaweed-gathering, I may specially mention the south coast of Devon; from Exmouth, where Bryopsis and Padina pavonia grow in perfection, to Torquay and the coves of Torbay, and down the coast to Plymouth, Cawsand Bay, and finally Whitsand Bay, the "happy hunting-grounds" of the enthusiastic algologist. On the north-east coast, Filey and Whitby must be mentioned, as well as the shores upwards from Tynemouth to Whitley. Peterhead is also a good locality, the rare Ectocarpus Mertensii, Odonthalia dentata, and Callithamnion floccosum being found there in abundance. Other favourable stations in Scotland, well known to me, are Lamlash Bay and Whiting Bay; nor must the Isle of Wight be forgotten, for in the rock-pools, at Shanklin especially, the most magnificent form of Padina pavonia may be found growing during the summer months in the utmost profusion.
In conclusion, I beg leave to inform my readers that I have recently published a volume on British Marine Algæ, in which every species that is likely to be met with by ordinary collectors is described, and every British seaweed that is capable of illustration in a work intended for popular information, is figured from plants in my own possession, and, in addition, diagrams and figures from drawings of magnified portions, illustrative of structure and fructification, appear throughout the pages of my work.