Fungi: Their Nature and Uses Part 25

[g] Hooker's "New Zealand Flora."

[h] Berkeley, "Sikkim Himalayan Fungi," in Hooker's "Journal of Botany" (1850), p. 42, &c.

[i] Montagne, "Cryptogamae Neilgherrensis," in "Ann. des Sci. Nat."

2^me ser. xviii. p. 21 (1842).

[j] Junghuhn, "Premissa in Floram Crypt. Javae."

[k] Zollinger, "Fungi Archipalegi Malaijo Neerlandici novi."

[l] Berkeley and Broome, "Fungi of Ceylon," in "Journ. Linn. Soc."

for May, 1871.

[m] "Flore d'Algerie, Cryptogames" (1846, &c.).

[n] Berkeley, in Hooker's "Journal of Botany," vol. ii. (1843), p.

408.

XIV.

COLLECTION AND PRESERVATION.

The mult.i.tudinous forms which fungi a.s.sume, the differences of substance, and variability in size, render a somewhat detailed account of the modes adopted for their collection and preservation necessary.

The habitats of the various groups have already been indicated, so that there need be no difficulty in selecting the most suitable spots, and as to the period of the year, this will be determined by the cla.s.s of objects sought. Although it may be said that no time, except when the ground is covered with snow, is entirely barren of fungi, yet there are periods more prolific than others.[A] Fleshy fungi, such as the _Hymenomycetes_, are most common from September until the frosts set in, whereas many microscopic species may be found in early spring, and increase in number until the autumn.

The collector may be provided with an ordinary collecting box, but for the Agarics an open shallow basket is preferable. A great number of the woody kinds may be carried in the coat-pocket, and foliicolous species placed between the leaves of a pocket-book. It is a good plan to be provided with a quant.i.ty of soft bibulous paper, in which specimens can be wrapped when collected, and this will materially a.s.sist in their preservation when transferred to box or basket. A large clasp-knife, a small pocket-saw, and a pocket-lens will complete the outfit for ordinary occasions. In order to preserve the fleshy fungi for the herbarium, there is but one method, which has often been described. The Agaric, or other similar fungus, is cut perpendicularly from the pileus downwards through the stem. A second cut in the same direction removes a thin slice, which represents a section of the fungus; this may be laid on blotting paper, or plant-drying paper, and put under slight pressure to dry. From one-half of the fungus the pileus is removed, and with a sharp knife the gills and fleshy portion of the pileus are cut away. In the same manner the inner flesh of the half stem is also cleared. When dried, the half of the pileus is placed in its natural position on the top of the half stem, and thus a portrait of the growing fungus is secured, whilst the section shows the arrangement of the hymenium and the character of the stem. The other half of the pileus may be placed, gills downward, on a piece of black paper, and allowed to rest there during the night. In the morning the spores will have been thrown down upon the paper, which may be placed with the other portions. When dry, the section, profile, and spore paper may be mounted together on a piece of stiff paper, and the name, locality, and date inscribed below, with any additional particulars. It is advisable here to caution the collector never to omit writing down these particulars at once when the preparations are made, and to place them together, between the folds of the drying paper, in order to prevent the possibility of a mistake. Some small species may be dried whole or only cut down the centre, but the spores should never be forgotten. When dried, either before or after mounting, the specimens should be poisoned, in order to preserve them from the attacks of insects. The best medium for this purpose is carbolic acid, laid on with a small hog-hair brush. Whatever substance is used, it must not be forgotten by the manipulator that he is dealing with poison, and must exercise caution. If the specimens are afterwards found to be insufficiently poisoned, or that minute insects are present in the herbarium, fresh poisoning will be necessary. Some think that benzine or spirits of camphor is sufficient, but as either is volatile, it is not to be trusted as a permanent preservative. Mr. English, of Epping, by an ingenious method of his own, preserves a great number of the fleshy species in their natural position, and although valueless for an herbarium, they are not only very ornamental, but useful, if s.p.a.ce can be devoted to them.

Leaf parasites, whether on living or dead leaves, may be dried in the usual way for drying plants, between folds of bibulous paper under pressure. It may be sometimes necessary with dead leaves to throw them in water, in order that they may be flattened without breaking, and then dry them in the same manner as green leaves. All species produced on a hard matrix, as wood, bark, etc., should have as much as possible of the matrix pared away, so that the specimens may lie flat in the herbarium. This is often facilitated in corticolous species by removing the bark and drying it under pressure.

The dusty _Gasteromycetes_ are troublesome, especially the minute species, and if mounted openly on paper are soon spoiled. A good plan is to provide small square or round cardboard boxes, of not more than a quarter of an inch in depth, and to glue the specimen to the bottom at once, allowing it to dry in that position before replacing the cover. The same method should be adopted for many of the moulds, such as _Polyactis_, etc., which, under any circ.u.mstances, are difficult to preserve.

In collecting moulds, we have found it an excellent plan to go out provided with small wooden boxes, corked at top and bottom, such as entomologists use, and some common pins. When a delicate mould is collected on a decayed Agaric, or any other matrix, after clearing away with a penknife all unnecessary portions of the matrix, the specimen may be pinned down to the cork in one of these boxes. Another method, and one advisable also for the _Myxogastres_, is to carry two or three pill-boxes, in which, after being wrapped in tissue paper, the specimen may be placed.

A great difficulty is often experienced with microscopic fungi, such, for instance, as the _Sphaeriacei_, in the necessity, whenever a new examination is required, to soak the specimen for some hours, and then transfer the fruit to a slide, before it can be compared with any newly-found specimen that has to be identified. To avoid this, mounted specimens ready for the microscope are an acquisition, and may be secured in the following manner. After the fungus has been soaked in water, where that is necessary, and the hymenium extracted on the point of a penknife, let it be transferred to the centre of a clean gla.s.s slide. A drop of glycerine is let fall upon this nucleus, then the covering gla.s.s placed over it. A slight pressure will flatten the object and expel all the superfluous glycerine around the edges of the covering gla.s.s. A spring clip holds the cover in position, whilst a camel-hair pencil is used to remove the glycerine which may have been expelled. This done, the edges of the cover may be fixed to the slide by painting round with gum-dammar dissolved in benzole. In from twelve to twenty-four hours the spring clip may be removed, and the mount placed in the cabinet. Glycerine is, perhaps, the best medium for mounting the majority of these objects, and when dammar and benzole are used for fixing, there is no difficulty experienced, as is the case with Canada balsam, if the superfluous glycerine is not wholly washed away. Specimens of _Puccinia_ mounted in this way when fresh gathered, and before any shrivelling had taken place, are as plump and natural in our cabinet as they were when collected six or seven years ago.

Moulds are always troublesome to preserve in a herbarium in a state sufficiently perfect for reference after a few years. We have found it an excellent method to provide some thin plates of mica, the thinner the better, of a uniform size, say two inches square, or even less.

Between two of these plates of mica enclose a fragment of the mould, taking care not to move one plate over the other after the mould is placed. Fix the plates by a clip, whilst strips of paper are gummed or pasted over the edges of the mica plates so as to hold them together.

When dry, the clip may be removed, and the name written on the paper.

These mounts may be put each in a small envelope, and fastened down in the herbarium. Whenever an examination is required, the object, being already dry-mounted, may at once be placed under the microscope. In this manner the mode of attachment of the spores can be seen, but if mounted in fluid they are at once detached; and if the moulds are only preserved in boxes, in the course of a short time nearly every spore will have fallen from its support.

Two or three accessories to a good herbarium may be named. For fleshy fungi, especially Agarics, faithfully coloured drawings, side by side with the dried specimens, will compensate for loss or change of colour which most species undergo in the process of drying. For minute species, camera lucida drawings of the spores, together with their measurements, will add greatly to the practical value of a collection.

In mounting specimens, whether on leaves, bark, or wood, it will be of advantage to have one specimen glued down to the paper so as to be seen at once, and a duplicate loose in a small envelope beside it, so that the latter may at any time be removed and examined under the microscope.

In arranging specimens for the herbarium, a diversity of taste and opinion exists as to the best size for the herbarium paper. It is generally admitted that a small size is preferable to the large one usually employed for phanerogamous plants. Probably the size of foolscap is the most convenient, each sheet being confined to a single species. In public herbaria, the advantage of a uniform size for all plants supersedes all other advantages, but in a private herbarium, consisting entirely of fungi, the smaller size is better.

The microscopic examination of minute species is an absolute necessity to ensure accurate identification. Little special remark is called for here, since the methods adopted for other objects will be available.

Specimens which have become dry may be placed in water previous to examination, a process which will be found essential in such genera as _Peziza_, _Sphaeria_, etc. For moulds, which must be examined as opaque objects, if all their beauties and peculiarities are to be made out, a half-inch objective is recommended, with the nozzle bevelled as much to a point as possible, so that no light be obstructed.[B]

In examining the sporidia of minute _Pezizae_ and some others, the aid of some reagent will be found necessary. When the sporidia are very delicate and hyaline, the septa cannot readily be seen if present; to aid in the examination, a drop of tincture of iodine will be of considerable advantage. In many cases sporidia, which are very indistinct in glycerine, are much more distinct when the fluid is water.

The following hints to travellers, as regards the collection of fungi, drawn up some years since by the Rev. M. J. Berkeley, have been widely circulated, and may be usefully inserted here, though at the risk of repet.i.tion:--

"It is frequently complained that in collections of exotic plants, no tribe is so much neglected as that of fungi; this arises partly from the supposed difficulty of preserving good specimens, partly from their being less generally studied than other vegetable productions.

As, however, in no department of botany, there is a greater probability of meeting with new forms, and the difficulties, though confessedly great in one or two genera, are far less than is often imagined, the following hints are respectfully submitted to such collectors as may desire to neglect no part of the vegetable kingdom.

"The greater proportion, especially of tropical fungi, are dried, simply by light pressure, with as much ease as phoenogamous plants; indeed, a single change of the paper in which they are placed is generally sufficient, and many, if wrapped up in soft paper when gathered, and submitted to light pressure, require no further attention. Such as are of a tough leathery nature, if the paper be changed a few hours after the specimens have been laid in, preserve all their characters admirably; and if in the course of a few weeks there is an opportunity of washing them with a solution of turpentine and corrosive sublimate, submitting them again to pressure for a few hours merely to prevent their shrinking, there will be no fear of their suffering from the attacks of insects.

"Many of the mushroom tribe are so soft and watery that it is very difficult to make good specimens without a degree of labour which is quite out of the question with travellers. By changing, however, the papers in which they are dried two or three times the first day, if practicable, useful specimens may be prepared, especially if a few notes be made as to colour, etc. The more important notes are as to the colour of the stem and pileus, together with any peculiarities of the surface, _e.g._, whether it be dry, viscid, downy, scaly, etc., and whether the flesh of the pileus be thin or otherwise; as to the stem, whether hollow or solid; as to the gills, whether they are attached to the stem or free; and especially what is their colour and that of the spores. It is not in general expedient to preserve specimens in spirits, except others are dried by pressure, or copious notes be made; except, indeed, in some fungi of a gelatinous nature, which can scarcely be dried at all by pressure.

"The large woody fungi, the puff-b.a.l.l.s, and a great number of those which grow on wood, etc., are best preserved, after ascertaining that they are dry and free from larvae, by simply wrapping them in paper or placing them in chip-boxes, taking care that they are so closely packed as not to rub. As in other tribes of plants, it is very requisite to have specimens in different stages of growth, and notes as to precise habitats are always interesting.

"The attention of the traveller can scarcely be directed to any more interesting branch, or one more likely to produce novelty, than the puff-ball tribe; and he is particularly requested to collect these in every stage of growth, especially in the earliest, and, if possible, to preserve some of the younger specimens in spirits. One or two species are produced on ant-hills, the knowledge of the early state of which is very desirable.

"The fungi which grow on leaves in tropical climates are scarcely less abundant than in our own country, though belonging to a different type. Many of these must constantly come under the eye of the collector of phoenogams, and would be most acceptable to the mycologist. But the attention of the collector should also be directed to the lichen-like fungi, which are so abundant in some countries on fallen sticks. Hundreds of species of the utmost interest would reward active research, and they are amongst the easiest to dry; indeed, in tropical countries, the greater proportion of the species are easy to preserve, but they will not strike the eye which is not on the watch for them. The number of fleshy species is but few, and far less likely to furnish novelty."

In conclusion, we may urge upon all those who have followed us thus far to adopt this branch of botany as their speciality. Hitherto it has been very much neglected, and a wide field is open for investigation and research. The life-history of the majority of species has still to be read, and the prospects of new discoveries for the industrious and persevering student are great. All who have as yet devoted themselves with a.s.siduity have been in this manner rewarded. The objects are easily obtainable, and there is a constantly increasing infatuation in the study. Where so much is unknown, not a few difficulties have to be encountered, and here the race is not to the swift so much as to the untiring. May our efforts to supply this introduction to the study receive their most welcome reward in an accession to the number of the students and investigators of the nature, uses, and influences of fungi.

[A] The genus _Chionyphe_ occurs on granaries under snow, as well as in that formidable disease, the Madura fungus-foot. (_See_ Carter's "Mycetoma.")

[B] Bubbles of air are often very tiresome in the examination of moulds. A little alcohol will remove them.

INDEX.

_aecidiacci_, structure of, 41.

_aecidium_ and _Puccinia_, 199.

germination, 141.

_Agaricini_, habitats of, 233.

structure of, 17.

Agaric of the olive, 108.

Agarics, growth of, 138.

Algo-lichen hypothesis, 10.

Alveolate spores, 130.

Amadou, 103.

American floras, 281.

fungi, 281.

Antheridia, presumed, 171.

Appearance of new forms, 248.

Arrangement of families, 80.