Chapter 4

Fig. 31. Young Plant ofIpomæa Quamoclit(from Decandolle's 'Organographie').

The great aim to be kept in view in collecting is to obtain as perfect and comprehensive a specimen as possible; that is, one showing every part of the plant—root, leaves, flowers, and fruit. It is not always practicable to show all these upon one specimen, and in such cases such a number must be selected as will carry out this plan. The wretched scraps with which some collectors content themselves are not only useless to their owners, but annoyances to everyone who has to do with them, or who is requested to pronounce an opinion upon them. Anyone who has had anything to do with naming plants for 'Science Gossip' or any other journal, which in this manner supplies information to its subscribers, will be able to testify to the large number of persons who do not scruple to send for determination single leaves, or a terminal shoot of a flowering plant, or a pinnule of a fern without fruit; a proceeding which is unfair to those to whom they are submitted, inasmuch as they either have to risk their reputation for accuracy, or to appear uncourteous by refusing to have anything to do with such specimens.

Fig. 32. Lime (Tilia Europæa).

Fig. 33. Beech (Fagus sylvatica).

Fig. 34. Sycamore (Acer pseudo-platanus), showing cotyledons and first and second pair of leaves.

To begin at the beginning, How rarely do we find the embryo of any species represented in a collection of dried plants? It ought to be there, not only as essential to the complete presentment of the history of the species, but as in certain cases indicating relationships which are not apparent when the plant is more advanced. Those who have not observed them would be surprised to find how much variety of form exists in the cotyledons alone, from thefleshy cotyledons of many of the Leguminosæ, the horse-chestnut, &c., to the foliaceous ones, or seed-leaves, of other plants. Among the latter may be noted and compared the lobed or palmate cotyledons of the lime (Fig. 32); the glossy dark green, somewhat kidney-shaped ones of the beech (Fig. 33); and the pinnatifid ones of the common garden cress (Lepidium sativum); the obcordate ones of the mustard or radish; the long, narrow, thin ones of thesycamore (Fig. 34); the sinuous or corrugated and bilobed ones of the walnut, and many more which willoccur to the observant reader, or which may be collected by anyone who will take the trouble to watch the germination of plants. And by making such collections, unexpected discoveries may arise, which will yet further confirm what has been said about the variety in form and structure even in these beginnings of growth. Plants which are, on accountof their general affinities, reckoned among the dicotyledons, may be found on investigation to have but one cotyledon, as Dr. Dickson observed to be the case with two of our butterworts,Pinguicula vulgarisandP. grandiflora, the third species,P. lusitanica, being dicotyledonous; or even to be acotyledonous, as is the case with the dodder (Cuscuta). In the latter-named genus, it is of importance to collect young specimens, as showing that the plant, although parasitic as soon as it comes in contact with a suitable foster-plant, is of independent origin. A search among young plants will no doubt lead to the discovery of some abnormalities, such as tricotyledonous embryos and other irregularities. Of some plants, such as the furze, the true leaves can only be found at an early stage of growth; in others, much variation may be noted in many points between the first leaves and the more perfect ones which succeed them; some, as the holly, at once developing leaves similar to those which are produced throughout the life of the plant, and others going through many modifications before the ultimate shape is attained, as in the ash, elder, ivy, maple, &c.

The roots or rhizomes also require to be much more fully represented and carefully collected than is usually the case. In every instance where the size of the plant does not prevent, the subterraneanand subaqueous parts should be carefully procured and preserved.

Dr. Trimen has lately directed attention to the corm-like tubers of the water plantain (Alisma),[G]closely resembling those of the arrowhead (Sagittaria), which have been described and figured by Nolte, but "do not seem to have been observed, or at least properly understood, in this country. They are buds remaining dormant through the winter, and containing a store of nutriment, to be employed in the development of the new plant from the tuber in the next year." Similar bulbs are developed by the frogbit (Hydrocharis). In determining many grasses and rushes, it is of importance to ascertain whether the rhizome is creeping or cæspitose, and it is therefore essential to collect good specimens. In the case of such plants as the coral-wort (Dentaria bulbifera) and toothwort (Lathræa squamaria), the root-stocks are eminently characteristic. Of such parasites as the broomrapes (Orobanche), some care is requisite in obtaining specimens in which the connection between the parasite and its foster-plant may be preserved and shown. The absence or presence of tubers should also be noted, and if present, they must be represented.

[G]'Journal of Botany,' 1871, p. 306.

Passing on to the leaves, we may note the importanceof obtaining in every case the root-leaves of each species. These are often very different in form from the stem-leaves, as in such species as the harebell (Campanula rotundifolia),Pimpinella saxifraga, the earth-nut (Bunium flexuosum), and many more; in some instances, as in the Jersey bugloss (Echium plantagineum), they at once characterize the species. Still more important are these lower leaves in the case of water-plants: in the arrowhead (Sagittaria), for example, they are narrow, and resemble those of the bur-reed (Sparganium); and in the water plantain (Alisma plantago), the submerged leaves are equally different from those which rise out of the water. This difference is still more noticeable in the case of the aquaticRanunculi, where a knowledge of the submerged leaves is essential to the discrimination of the various forms or species.

Where practicable, the whole plant should be collected for the herbarium; but when, from its size, this cannot be accomplished, leaves from the root, the centre of the main stem, and the lateral branches, should be taken. As to the stem itself, that must be represented: in theRubi, indeed, it is essential. "To judge properly of a bramble from a preserved specimen," says Professor Babington, "we require a piece of the middle of the stem with more than one leaf; the base and tip of the stem are also desirable,likewise a piece of the old stem with the flowering shoot attached to it; the panicle with flowers, and the fruit. We likewise want to know the direction of the stem throughout, of the leaflets, and of the calyx; also the shape of the petals and the colour of the styles: a note of these should be made when the specimen is gathered."

Passing on to the flowers, we shall find it necessary to represent them in almost every stage, from the bud to the perfecting of the fruit. It is of course in most cases possible to select an example in such a state as to show upon the same plant buds, flowers, and fruits; but where this is not the case, each of these particulars must be supplemented by additional specimens. The turn which botanical investigation has recently taken towards the study of the phenomena connected with fertilization has given the collector another subject to which his attention may be profitably directed. It has been observed that in some plants the stamens are developed before the pistils; in others, the pistils are matured before the stamens; while in yet a third set, stamens and pistils are simultaneously perfected. These three groups of plants are termed respectively protandrous, protogynous, and cynacmic, and a very little observation will show that examples of each are sufficiently common.

Then in diœcious and monœcious plants, both male and female flowers must be collected, and in some cases, as in the willows, four specimens are necessary to the complete presentment of the species, showing respectively the male and female catkins, the leaves, and the fruit. Some plants produce two distinct forms of blossom, as is noticeable in the violets and the woodsorrel, one being conspicuous and usually barren, the other insignificant and often apetalous, but producing perfect fruit. The pollen will afford occupation to the microscopist: the researches of Mr. Gulliver and Mr. Charles Bailey have demonstrated that important distinguishing characters are in some instances furnished by it. While on this point it may be suggested that it is convenient in many cases to collect several specimens of the flowers alone, which, when dried, should be placed in a small envelope or capsule, and attached to the sheet on which the plant is represented. In the event of any examination which may be requisite after the plant is dried, these detached blossoms will be found very useful, and will prevent the necessity of damaging the specimen. In the case of such plants as shed their corollas very readily, as the speedwells, it is as well to put them in press as soon as collected; and the colour of many may be retained by the same means.

The fruits and seeds of plants are too generally neglected by amateur collectors, but are essential to the completeness of a specimen. It may be found practically convenient to keep these in a separate place, and detached from the plant; and in many cases of dried fruits it is advisable to sort them into their places without previous pressing. By this means the modes of dehiscence will readily be seen: pulpy and succulent fruits should be preserved in spirit. In such plants as the species of sea sandwort (Lepigonum), and some Chenopodia, important specific characters are drawn from the seed; as they are from the pods ofMelilotusand the fruits ofAgrimonia. In collecting ferns, well-fruited fronds must be selected, as it is impossible to determine specimens without fructification. Grasses should be selected when in flower and fruit, but must not be allowed to attain too great an age before they are collected.

We have been speaking so far of the things to be collected, and space will not allow us to dilate at any length upon the apparatus necessary to that end. Nor indeed is this necessary; a good-sized vasculum, with one or two smaller boxes for the pocket, in which the more delicate plants may be preserved; a strong pocket-knife or small trowel, for procuring roots, and a hooked stick wherewith to fish out water-plants, or pull down branches, are theprincipal things required. To anyone residing for any length of time, or even only for a few days, in a district, a "London Catalogue" is an important acquisition, in which should be marked off all the species met with; by this means the flora of the neighbourhood is ascertained at a very slight expenditure of time and trouble. It is not advisable to collect too many plants at once, or to crowd the vasculum, unless under exceptional circumstances; nor should the desire to possess rare plants tend, as is too often the case, to the neglect and exclusion of commoner ones.

A careful and observant collector will frequently meet with forms which deviate more or less from the accepted type of a species. When these appear to offer any marked characters, they should be noted; and in all cases it is well to preserve any forms which, from external circumstances, have a different appearance from the normal state. The differences produced by soil and situation alone are very considerable; and though the essential characters are usually to be discerned, the interest and value of a herbarium are very much increased by a selection of examples showing the range of a species.Campanula glomerataoffers a good example of this. In damp meadows it is from one to two feet high, with a large spreading terminal head of blossoms, while onchalk downs it does not attain more than as many inches, with only one or two flowers; in this state it was described by Withering as a gentian, under the name ofGentiana collina; and the same author gives asCampanula unifloraa one-flowered mountain state of the harebell (C. rotundifolia).

The collector will also do well to keep a look-out for deviations in structure, which are often of great interest. In short, nothing should be neglected which can tend to the perfect presentment of a species in the herbarium: its utility is commensurate with its completeness. The mere collector may be satisfied with scraps of a rare plant and the absence of commoner species; but the real worker will pride himself rather upon the possession of instructive examples, which may be of assistance to himself, as well as to all those who may consult them.

IX.

FLOWERING PLANTS AND FERNS.

By James Britten, F.L.S.

PART II.

We will assume that our collecting for the year has come to a close; that the long evenings are beginning, and that our dried plants have been brought together from their temporary resting-places to be revised and selected from, so that they may be intercalated in their places in the herbarium, if we already possess one, or, if we are as yet quite novices, that they may form a nucleus around which the whole British flora shall be gathered in due course. First of all, we must make all necessary preparation for—

Mounting, the first essential to which is paper. Much of the neatness of a herbarium depends upon its uniformity, so that it is desirable to lay down a definite plan at the beginning and to act up to it consistently. Amateurs often spoil specimens which they have collected and preserved with considerable care by transferring them from one sheet to another; from books—but it is onlyveryamateur botanistswho keep their plants in this way!—to loose sheets, from small paper to large, and so on; each change being attended with some slight damage to the specimen so treated. It is, I believe, the common practice on the Continent to keep the specimens loose in folded sheets of paper; but this plan is not followed in England, and although advantageous, as permitting the fullest examination of the plant, it is attended with much risk to the specimens in the way of breakage; so that we may consider it settled that we are going to fasten our plant down upon a sheet of paper. This must be rather stout, and large enough to admit the full representation of the species. The sheets used at the Kew Herbarium are 16-1/2 inches long by 10-1/3 inches wide; those employed at the British Museum are 17-1/2 inches by 11-1/4 inches; but the former will be found amply sufficient for our purpose. The next consideration is the means by which the specimens are to be secured, which are more various than might at first be supposed. Some persons sew them to the paper; others place straps over them, which are secured with small pins; but the choice practically lies between fixing the whole specimen to the paper with gum, paste, or glue, or securing it with straps of gummed paper. The former plan, which is that adopted at our great public herbaria, is certainlybetter for specimens which are likely to be much consulted; but the latter is in some respects more satisfactory, if somewhat tedious, as it admits the removal of the plant to another sheet if necessary, and delicate portions, such as thin petals or leaves, are not injured as they are when gummed down. At the British Museum and Kew a mixture of gum tragacanth and gum-arabic (the former dissolved in the latter), in about equal parts, is used for this purpose; but very coriaceous specimens are secured with glue at the last-named establishment, while in the former the stems and ends of branches are usually also secured with straps. When the specimen is entirely gummed down, it is a good plan to keep a few extra flowers or fruits in a small capsule attached to the sheet: these will be useful if it is required to dissect such portions, and the specimen need not be injured for such purpose.

Poisoning.—Some persons are in the habit of employing a solution of corrosive sublimate for the purpose of washing over their plants when mounted, and so preventing the development of animal life. The solution in use at the Kew Herbarium is composed of one pound of corrosive sublimate, and the same quantity of carbolic acid to four gallons of methylated spirit; this fulfils the purpose for which it is intended very well, but is somewhat disagreeableto use. At the British Museum it is found that the presence of camphor, frequently renewed in each cabinet, is sufficient to prevent the attacks of insects. It will soon be discovered that some plants, such, for example, as theUmbelliferæandGrossulariaceæ, are peculiarly liable to such attacks; and these orders must be inspected from time to time, so that any insect ravages may at once be checked. Damp is to be avoided in the situation of the herbarium, as it favours the development not only of insects but of mould, and renders the specimens rotten.

The question oflabellingis of some importance, especially to those who value neatness and uniformity in the appearance of their herbarium. One or two sets of printed labels for this purpose have been issued, but they cannot be recommended. They give more than is necessary, e.g. the English, or, more correctly, the book-English names, the general habitats, and definite localities of rare species, and allow very insufficient space for filling in the date and place of collecting, the name of the collector, and such remarks as occasionally occur. The plan of writing all necessary information upon the sheet itself is a good one; but those who prefer a uniform series of labels will find that a form like the following is as useful as any which they can adopt, and includes all necessary information. Thesize here given will be adequate for almost all requirements, and is a "happy medium" between the small tickets upon which we have animadverted, and the enormous ones with which some botanists think it necessary to accompany their specimens. Care should be taken to avoid the possibility of a misplacement of labels; many serious blunders have arisen from the neglect of due precaution in this matter.

Herb. John Smith.Ranunculus acris, L.& R. Steveni, Reich.Loc.Meadows near Barchester.Date, June 30, 1874.Coll.John Smith.

Herb. John Smith.

Ranunculus acris, L.& R. Steveni, Reich.

Loc.Meadows near Barchester.

Date, June 30, 1874.

Coll.John Smith.

Arrangement.—The plants, being now affixed to their respective sheets and duly labelled, are ready to be placed in covers, and rendered available for ready reference. Each genus will require a separate cover, which may well be of somewhat stouter paper than that on which the plants are mounted; the name of the genus should be written at the left-handcorner, followed by a reference to the page of the manual by which the plants are arranged, or to the number which it bears in the "London Catalogue," if that be employed in their arrangement—a purpose for which it is very suitable. Should the species be represented by more than one sheet, it is convenient to inclose each in a cover of thinner paper, which may bear the number assigned to the plant in the right-hand corner; and it is also convenient to write the name of the plant at the bottom of each sheet, and to number it also in the right-hand corner. These details may appear trivial, but they in reality affect in no small degree the readiness with which any species may be referred to. Should the plants be arranged in accordance with the "London Catalogue," a copy should be kept with the herbarium, in which the plants should be ticked off, so that it may serve as a catalogue of the species represented.

Cabinets.—It will of course be necessary to provide some accommodation for our specimens, and for this purpose we shall find no better model than the cabinets in use in the Botanical Department of the British Museum. The accompanying figure (drawn to scale) is an exact representation of one of these. The measurements can of course be modified so as to suit the size of the herbarium sheets. Each shelfis a separate drawer, which with its contents can be taken out and replaced at will. Two cabinets such as that figured will be found amply sufficient to contain a very good British herbarium. At Kew the cabinets employed are somewhat similar, but their height is greater and the shelves are fixed.

Fig. 35. Cabinet for Herbarium Sheets.

The above are the principal points connected with the arrangement of a herbarium, considered as distinct from the work of collecting. It is possible that I may have omitted to touch upon certain details which may occur to the amateur; should such be the case, I may add that I shall be happy to supply any additional information, either by letter or by word of mouth; or to show the system adopted at the British Museum to anyone who may call upon me there for further hints upon the subject.

GRASSES, ETC.

By Professor Buckman, F.G.S., etc.

Grasses form such a distinct group of plants, and their study is so often undertaken for special purposes, that a few remarks upon their collection and preservation can hardly be considered as out of place in this little manual.

Delicately as grasses are formed, yet it cannot be said that their tissues are so liable to injury, or their colours so evanescent, as those of the flowering plants which the botanist ordinarily delights in. Nor indeed are the grasses so succulent as many other herbs. In this respect they may be said to hold a place between ferns and those plants which usually are called flowers.

Again, in the dried state their organs are generally so well preserved as to present all that a botanist can wish for, for identification as well as arrangement; and the student of grasses ever finds his collection to contain beauties not only in point of rarity, but as regards delicacy of structure and grace of outline.

Viewing them in this light alone, we have oftenbeen astonished that so many students of plants pay so little attention to them, and this feeling is enhanced when the great value of the grasses is considered.

If then a few simple directions for preserving these plants shall have the effect of winning a convert to these views, we shall be delighted; and to this end we shall make our descriptions as plain as our process has ever been easy and simple, and yet complete.

In collecting grasses, as in other tribes of plants, it will be necessary that our specimens should be chosen with the view to exhibit every feature of interest. With this aim, then, it will be best in the general way to obtain as much of the plant as possible, so that it may be necessary to get them up by the roots. Still, in many species the root is not of much importance: but there are a few which possess rhizomata, or underground stems; such as theTriticum repens,Poa pratensis,P. compressa,Holcus mollis,Agrostis stolonifera, and others. These should always exhibit these parts; and as such examples are usually agrarian, it is easier to mark down desirable specimens and seek a fork at the neighbouring farm-buildings wherewith to completely get them out, than to carry any substitute in a smaller and less perfect implement.

Haying made these remarks, we will suppose that we are now about to sally forth in search of grasses; in which case we make the following preparations.

As we do not file our copy of the 'Times' we make use of it as collecting-paper as follows:—Each side of the paper is cut in two, or, as a Cockney would say, "in half." Each half is then folded into a double collecting-sheet, and as many of these are taken as are likely to be useful. In each of these papers is put a small slip of writing-paper, on which to note the locality and any other noteworthy fact connected with a specimen when put in the paper. These papers, separately folded, are placed with the open ends inwards in a convenient portfolio, and the collector is ready to take the field.

Of course there will be those who will advocate Bentall's drying-paper, blotting-paper, and so on, and we would not have it supposed that we despise these luxuries; but as we have found the plan advocated always to answer the purpose for grasses, we have felt independent of the more refined collecting-papers.

Now let us suppose that we have gathered fifty specimens, and have returned home. The next thing will be to put them as soon as may be in a position for drying.

Our drying apparatus then consists of half-a-dozensmoothly planed deal boards, and for our first collection we take two of these, and upon one we lay some few folds of our old 'Times' then a specimen in their papers (having previously improved their arrangement, when necessary), and then some more folds of paper, and proceed as before, until all the specimens have been placed; then put a board on the top sheet, and upon that a stone, or a 7 or 14 lb. weight, according to the size and quantity of the specimens. If another day's collection of specimens be made before the foregoing are dry, they may be arranged in the same way on the top board, and another board used and the weight replaced. The object of this is to keep partially dried from fresh specimens, the putting together of which is a fertile source of mildew and decay.

In arranging our specimens for the herbarium, we procure sheets of cartridge paper 18 inches long by 11 inches wide, using a folded sheet for each species.

In these papers the specimens are fastened down in the following manner:

Gum over a portion of the cartridge paper (so as to have the same colour) with two consecutive coats of a clean solution of gum-arabic.

This can be cut into slips of any length and breadth, making them as narrow as possible for the sake of neatness, and when the specimen is placed in itspaper, a few of these slips may be made to confine it in the desired position. Each example is then to be labelled at the bottom of the sheet, and each label should set forth—a, Its botanical name;b, its trivial or local name;c, the locality whence it was obtained;d, the date when gathered; added to which, if presented, the donor's name.[H]

[H]Printed herbarium labels may be got at Messrs. Hardwicke and Bogue's, the publishers.

The sheets so prepared may be arranged in groups or genera, each being folded in convenient paper or cloth wrappers, and the whole arranged in volumes of stiff covered portfolio.

This, then, is all that seems to us necessary in the collection and preservation of grasses; but we would recommend the student, if an artist, to make a typical specimen of each sit for its portrait. In this way we have made drawings of all the species and varieties that have come in our way.

Our drawings are life-size, usually lined in with Indian ink with a fine "lithographic pen." These we partially colour on the spot.

The anatomical details are much enlarged and always fully coloured. To this end ourimpedimentafor a day among the grasses consist of, besides the collecting portfolio, a sketching block, large octavo size, and a small box of soft colours. Armed withthese we have made many a drawing of a grass under the shade of a tree, or in the parlour of some contiguous inn.

Lastly, we would venture to remark, if, besides the interest which grasses should have for the student of botany, these plants be viewed, as they have ever been by us, as indicators of the nature of soil and the value and capabilities of the land on which they grow, the collector should not fail to make notes connected with the soil, situation, and other practical facts connected with the habitats ofGrasses.

XI.

MOSSES.

By Dr. Braithwaite, F.L.S., etc.

In making a collection of the vegetable productions of a country we find considerable differences in the structure of the various groups of plants, and in the tissues of which they are composed; and hence special manipulation is requisite in dealing with certain orders. Some are of so succulent a nature, or have a framework so easily disintegrated, that they contain within themselves the elements of destruction, and present the greatest difficulty in satisfactory preservation, while others are so slightly acted on by external agents, that little trouble is required to prepare specimens of permanent beauty.

The Ferns and Lycopods, being generally appropriated by the collector of flowering plants, will be treated on with the latter, and following these come the Mosses, to which we will now direct attention, taking the alliance in its broadest sense, as including the three groups of Frondose Mosses, Bog Mosses, and Liver Mosses, or Hepaticæ, all of which are readilycollected and preserved, and yield an endless fund of instructive entertainment to the microscopist. But it may be asked, Where is the game to be found? Where are the pleasant hunting-grounds in which they most do congregate? We answer, everywhere may some species or other be met with; yet, though many are cosmopolitan, the majority have their special habitats, and some their special seasons, both being considerably influenced by the presence of moisture.

Collecting.—The bryologist has one advantage over the phænogamous botanist, for it is not imperative that mosses should be laid out and pressed immediately; and hence less care is required in collecting them, than is bestowed on flowering plants; the necessary apparatus is confined to a pocket-knife, to remove specimens from stones or trees, a stock of stout waste paper, and a vasculum, or, better still, a strong bag, in which to carry the packets. When collecting the plants, it is well to remove any superfluous earth or stones, or to squeeze out the water from those found in bogs; and then each is to be wrapped separately in paper, and the locality marked outside; or the more minute species may, for greater safety, be placed in chip boxes. On reaching home, if we do not prepare the specimens at once, we must not leave the parcels packedtogether in their receptacle, or mould will soon attack them and spoil the whole; but we must spread them out on the floor until quite dry, and then reserve them to a convenient opportunity to lay out; as in the dry state they may be kept for years unchanged.

It often happens that our line of study is developed by some fortuitous circumstance. A neglected flowerpot in the corner of the garden attracts attention by its verdant carpet of moss, or, peeping over the wall, we see the crevices between the bricks bristling with capsules ofTortula muralis, the red twisted peristome freshly brought to view by the falling away of the lid, and, taking a bit indoors to submit to the microscope, we are so captivated therewith that we then and there determine to become a bryologist. Nor is this all that a journey round the garden will disclose: the neglected paths yield other species not less worthy of examination, and old apple-trees are not unfrequently tenanted by mosses.

Extending our walks to the commons, lanes, and woods, we may find on the ground and banks, in bogs and on the stumps and trunks of trees, a number of species greatly extending our list; while others again are only met with on the clay soil of stubble-fields, as various species ofPottiaandEphemerum: appearing in October, their delicate textureis developed by the constant moisture of winter, and with it also they vanish, to appear no more until the succeeding season. Travelling yet farther away, we find that each locality we visit yields some novelty: old walls and rocks of sandstone or slate, limestone districts, and, above all, a mountainous country, are rich in species we seek in vain elsewhere. Here peat bogs, and rocks dripping with water, ever supplied by the atmosphere, or the tumbling streams everywhere met with, are the chosen homes of these little plants, and thither must the collector resort, if he would reap his richest harvest. Winter and spring in the lowlands, and a later period in the elevated districts, will be found most productive of fruiting plants.

Preparation of Specimens.—So rapidly does the cellular texture of the mosses transmit fluid, that, when soaked in water, we see them swell up and expand their little leaves, and in a short time look as fresh as when growing; hence a basin of water, a towel, and drying-paper are all we require to prepare our specimens for the herbarium. If the tufts are large, we must separate them into patches sufficiently thin to lie flat, and by repeated washing, get rid of adherent earth, mud, or gravel. This is conveniently accomplished by holding the tuft in the palm of the hand, under a tap, and allowing a stream of water to pass through it; then by pressurein the folding towel we remove superfluous moisture and immediately transfer to paper, arranging the plants as we wish them to lie permanently, and placing with each a ticket bearing the name: a moderate weight is sufficient to dry them, as with great pressure the capsules split, and thus the value of the specimen is decreased. It not unfrequently happens that two or three species grow intermixed: these must be carefully separated at the time of soaking, and any capsules required to show the peristome must also be removed before the plants are submitted to pressure.

Examination of Specimens.—We have very much to learn about a moss before we can become masters of all the characters that pertain to it as a specific individual. We must observe its branching, the mode of attachment of the leaves to the stem, and their direction; the form and structure of a separate leaf, the position of the male flowers, and, lastly, the position and structure of the fruit. For the efficient determination of these we require a microscope (the simple dissecting microscope is amply sufficient), a couple of sharp-edged, triangular needles fixed in handles, and a few glass slides and covers. Having soaked our specimen in water, we lay it on a slide, and by cutting through the stem with one of the needles, close to the attachment of a leaf, we can readily remove the leaf entire, and two or threemay be transferred to another slide, and placed in a drop of water under a cover: the same thing may be roughly accomplished by scraping the stem backwards with one of the needles; but in this way the leaves are often torn.

Fig. 36.Tortula muralis.a.Leaf and its areolation.b.Capsule.c.Calyptra.d.Lid.e.Male flower.f.Antheridia and paraphyses.

By examination of a leaf we notice its form, the condition of its margin, whether entire or serrated or bordered; the presence and extent of the nerve; and lastly, and most important of all, the form and condition of its component cells; and for this a higher power is required. With a 2/3-inch object-glass and C eyepiece we can observe their form, and whether their walls are thickened so as to renderthem dot-like; their contents, whether chlorophyllose or hyaline; and their surface, whether smooth or covered with papillæ; for often these points are so characteristic, that by them alone we can at once refer a barren specimen to its proper family or genus.

Preservation of Specimens.—This may be discussed under two heads: 1st, as microscopic objects; 2nd, for the herbarium.

1. The parts required for microscopic examination are the capsules and peristome, entire specimens of the smaller species, and detached leaves. The capsules having to be viewed by condensed light, must be mounted dry as opaque objects; and for this purpose I use Piper's wooden slides, with revolving bone cover; and in one of these we may fix a capsule with the lid still attached, another laid on its side, but showing the peristome, and a third with the mouth of the capsule looking upward, a position very useful for the species ofOrthotrichum, as we are thus enabled to see the inner peristome; and with them also may be placed the calyptra: should the cost of these be an object, a cheaper substitute may be found in shallow pill-boxes, blackened on the inside.

To preserve the leaves in an expanded state we may employ the fluid media used for vegetabletissues, or, when time is of consequence, Rimmington's glycerine jelly is a convenient material in which to mount them, a ring of dammar cement being first placed on the slide, and within this the liquefied jelly, to which the expanded specimen is quickly transferred, and the cover securely sealed by gold size. Preparations of this kind are of the highest value as types for comparison with actual specimens we may have for determination.

Fig. 37.Ceratodon purpureus.a.Male plant. 1. Leaf and its areolation. 2. Capsule. 3. Calyptra 4. Two teeth of the peristome.

2. In mounting specimens for the herbarium we must be guided by the limits which we have fixed on for the extent of the same; and I may first describe the method adopted for my own collection.Every species has a separate leaf of cartridge-paper measuring 14-1/2 × 10-1/2 inches, and on this the specimens are fixed, each mounted by a little gum on a piece of toned paper; thus 4 or 6 to 12 specimens, according to size, are attached to each leaf,—varieties have one or more additional leaves; and to each is also fixed a triangular envelope, inclosing loose capsules and leaves for ready transfer to the microscope, and also a label indicating the name, habitat, and date of collection. A pink cover for each genus includes the species, and a stout millboard cover embraces the genera of each family, with the name of which it is labelled outside, the whole shutting up in a cabinet.

Another form is that seen in Rabenhorst's Bryotheca Europæa, quarto volumes of 50 specimens, one occupying each leaf, and so arranged that the specimens do not come opposite to each other. Others again use loose sheets of note-paper, within each of which a single specimen is mounted; but this, from their size, is very cumbersome. Or we may take a single well-chosen typical specimen and arrange many species on a page, as is seen in the beautiful volume of Gardiner's 'British Mosses' or McIvor's 'Hepaticæ Britannicæ.' Whatever plan we adopt, our specimens, once well dried and kept in a dry place, are unchangeable, and are always lookedupon with pleasure, each recalling some pleasing associations, or perchance reminding us of some long-lost friend, in companionship with whom they were collected or studied. A stock of duplicates must also be reserved, from which to supply our friends, or exchange with other collectors for desiderata in our own series: these may be kept in square cases of various sizes, cut so as to allow the edges of the top and sides to wrap over the other half folded down on the specimens.

The Hepaticæ of the family Jungermanniaceæ are treated precisely as mosses, the capsules, however, show but little diversity, and will not require separate preservation; but the elaters, or spiral threads accompanying the seeds, are elegant microscopic objects. The Marchantiaceæ must be pressed when fresh, as they do not revive with the same facility as other species, owing to their succulent nature and numerous layers of cells.

Classification.—On this I have fully treated elsewhere ("The Moss World," 'Popular Science Review,' Oct., 1871), and it may suffice here simply to indicate the families of British mosses and their mode of arrangement. The cell-texture of the leaf takes an important place in the characters, and in accordance with this principle the Cleistocarpous or Phascoid group is broken up and distributed in various families.We have two orders; one indeed, comprising only the genusAndreæa, is distinguished by the capsule splitting into four valves united at apex; the other, including the bulk of the species, has in most cases a lid, which separates transversely, and usually discloses a peristome of tooth-like processes. The structure of these teeth again enables us to form three divisions. In the first they consist of a mass of confluent cells; in the second, of tongue-shaped processes, composed of agglutinated filaments; and in the third, of a double layer of cells, transversely articulated to each other, the outer layer composed of two rows of firm coloured cells, the inner of a single series of vesicular hyaline cells, on which the hygroscopic quality of the tooth depends.

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