Flowers and Sea Weeds
The apparatus required for the preservation of the wild flowers of our cliffs, and the sea weeds, consists of a quantity of blotting paper or other thick absorbent paper cut to a convenient size, a few thin boards and a few pieces of calico of the same size, some heavy weights, and several sheets of drawing paper.
The wild flowers are arranged on the sheets of absorbent paper while still fresh, care being taken to display the principal parts to the best advantage. They are then placed in a single pile, with a few extra sheets of absorbent paper between each two specimens to facilitate the drying, boards at the bottom and top as well as at equal distances in the midst of the pile, and the weights on the top of the whole.
The natural colours of leaves and flowers are not very often preserved satisfactorily, but the best results are obtained when the drying process proceeds most rapidly. Hence, if the press contains any specimens of a succulent or sappy nature, they should be taken out after the first day or two, and then replaced with a fresh supply of dry paper.
The flowers must be left in the press until quite dry, and they may then be mounted on sheets of drawing paper, by fixing them with a little gum tragacanth, or by narrow strips of gummed paper passing over their stems.
Some collectors prefer simply placing their botanical specimens inside double sheets of drawing paper, not fastening them at all, and there is much to be said in favour of this, especially as it allows the specimens to be examined on both sides; and even when they are fastened to the paper double sheets are much to be preferred, for the specimens are not then so liable to be damaged by friction when being turned over, especially when the names are written on the outside of each sheet.
The larger sea-weeds may be dried in the same manner, though it is a good plan to absorb the greater part of the moisture they contain by pressing them between pieces of calico previous to placing them in the ordinary press. It should be observed, however, that many sea-weeds exude a certain amount of glutinous substance that makes them adhere to the paper between which they are dried, while they do not so freely adhere to calico. These should be partially dried in the calico press, and then laid on the paper on which they are to be finally mounted, and re-pressed with a piece of dry calico on the top of each specimen.
Many of the smaller weeds may be treated in the manner just described, but the more delicate species require to be dealt with as follows:—Place each in a large, shallow vessel of water, and move it about, if necessary, to cause its delicate fronds to assume that graceful form so characteristic of the algæ of our rock pools. Then immerse the sheet of paper on which the weed is to be finally mounted, and slowly raise the specimen out of the water, on the paper, without disturbing the arrangement of the fronds. If it is found necessary to rearrange any of the fronds, it may be done by means of a wet camel-hair brush. Now lay the specimen on calico or absorbent paper, placed on a sloping board, to drain; and, after the greater part of the moisture has disappeared by draining and evaporation, transfer the specimen to the press with a piece of dry calico immediately over it. All are dealt with in turn in the manner described, and allowed to remain in the press until perfectly dry, when it will be found that the majority of them have become firmly attached to the mount, and require nothing but the label to fit them for the herbarium.
Sea-weed collectors often make the great mistake of pressing tufts that are far too dense to admit of the structural characters being satisfactorily examined. To avoid this fault, it will often be necessary to divide the clusters collected so that the forms of their fronds may be more readily observed.
The calcareous corallines may be pressed in the same way as the other algæ, but very pretty tufts of these, having much the appearance of the living plant, may be obtained by simply suspending them until thoroughly dry; though, of course, specimens so prepared must not be submitted to pressure after they are dry, being then so brittle that they are easily broken to pieces.
The hard framework of these interesting corallines is composed principally of carbonate of lime, a mineral substance that dissolves freely in hydrochloric acid (spirits of salt). Thus, if we place a tuft of coralline in this acid, which should be considerably diluted with water, the calcareous skeleton immediately begins to dissolve, with the evolution of minute bubbles of carbonic acid gas; and after a short time, the end of which is denoted by the absence of any further bubbling, nothing remains but the vegetable matter, now rendered soft and pliant. A decalcified specimen of coralline may be pressed and dried, and then mounted beside the plant in its natural condition for comparison; and the true appearance of the vegetable structure may also be retained, and in a far more satisfactory manner, by preserving a portion of the specimen in dilute spirit.
Finally, it may be observed that many sea-weeds, like wild flowers, do not retain their natural forms and colours when preserved dry. They are spoilt by the pressure applied, or become so shrivelled and discoloured in the drying as to be but sorry representatives of the beautifully tinted and graceful clothing of the rocks of the coast. But many of those that suffer most in appearance when dried may be made to retain all their natural beauty by preserving them in a fluid; and it is most important that this should be remembered by all who desire to study the weeds at home, and particularly by those who possess a microscope, and wish to search into the minute structure of marine algæ. Our own plan is to keep not only the dried specimens for the purpose of studying the general characters and classification of the algæ, but also to keep a few large bottles—stock bottles—filled with weeds of all kinds in a preservative fluid. These latter are exceedingly useful at times, and are frequently brought into requisition for close inspection, with or without the microscope. Small pieces may be detached for microscopic examination when required, and sections may be cut either for temporary or permanent mounting just as well as from living specimens, such sections showing all the details of structure exhibited by the living plant.