Fungi: Their Nature and Uses

by M. C. Cooke

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, Sphæria, 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 Pezizæ 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 repetition:—

“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 phœnogamous 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-balls, and a great number of those which grow on wood, etc., are best preserved, after ascertaining that they are dry and free from larvæ, 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.