IF, in offering a few practical suggestions, we either repeat ourselves, or communicate common-place hints, those who may know already all we shall essay to tell them will please to pardon and pass on.

All the information essential under this head relates to collecting, examining, and preserving microscopic fungi.

Collecting does not differ, except in the objects themselves, from any other botanical collecting. Those who attempt it must be prepared to sacrifice their kid gloves and patent-leather boots, to put on waterproofs and perseverance, and come home sometimes disappointed. The requisites for good work are but few, and easily supplied. A strong knife, a pocket lens, and a box or leather bag, will be all that is really essential. But where shall we go—and when? Hedge-banks, the sides of ditches, borders of woods, anywhere, if the plants are to be found on which the fungi are parasitic. We flatter ourselves on being rather successful in collecting, and our favourite localities have always been the dampest places in woods, railway-banks, and waste places. It is a great mistake to endeavour to go over a large tract of ground. We have spent a whole day in a little chalkpit, which had fallen into disuse, and grown wild. Fifty yards into a wood is as much, as we attempt, when alone; and a spot six yards square has afforded us occupation for hours. It is better to examine a small space thoroughly than to scamper on, mile after mile, and find nothing.

When? is as much to be noted as where! All the year round we shall be sure of finding something of interest. As soon as the last patch of winter’s snow has melted from the ground, and green leaves begin to unfold themselves, the search may begin. Cluster-cups (Æcidium) will be the earliest forms encountered. On the leaves of Lapsana communis, and the pilewort, these will be found before the majority of plants have burst their buds. Henceforth, other forms will gradually appear, until May or June. One or two species of Puccinia will be seen in April or May, but from that period until autumn, species of Trichobasis will be common. In June and July the smuts belonging to the genus Ustilago are most plentiful, and from August to October Puccinia and its allied genera will have the ascendant; so that from March to October there is continually succeeding each other some species of parasitic fungus belonging to the Uredines. From October to March need be no more a season of repose from the search of these minute plants than from March to October. So long as the ground is not covered with snow there will always be something to find on dead leaves, rotten sticks, &c., when there is not a green leaf to be seen. But these belong to a section to which we have studiously avoided all reference in the foregoing pages.

General instructions will not always apply; but in most instances, the lowest and earliest leaves, in which vitality appears to decline, will be most likely to suffer from the attacks of fungi. This rule must not be too stringently applied; the species of Æcidium, for instance, will generally be found on vigorous green leaves.

Having found a plant infected with some rust or brand, and by means of a pocket lens assured yourself that it is such, although the power is insufficient to tell what it is, collect as many leaves as you are likely to require; place them flat one upon the other, to prevent their curling up at the edges, should the weather be hot, and yourself far from home, and lay them in your box; or if you should take in preference an old book with stiff covers, place them separately between the leaves of your book, and they will be in still better condition, if you desire to preserve them. Arrived at home with the results of your trip, proceed at once to lay them between folds of blotting-paper, submit them to a gentle pressure, and change the papers daily until your leaves are dry, not forgetting to keep a scrap of paper with each collection, stating date and locality, to which, after microscopical examination, the name may be added. When thoroughly dry, your leaves may be preserved for reference in old envelopes, with the particulars endorsed on the outside. Fungi on leaves will generally be examined to the greatest advantage in the fresh state, but if too much pressure is not employed in the drying, it will not be difficult even in that condition to make out their characteristic features. Care must be taken, by changing their position, that moulds of other kinds do not establish themselves upon the specimens in drying, or that when dried they do not fall a prey to Eurotium herbariorum.

If it is intended to add these leaves to your herbarium, or to form a special herbarium for them, they should be mounted on white paper, first by affixing one or two leaves by means of thin glue to a paper about four inches square, on which the name, date, and locality may be written, and attaching several of these species-papers to a larger or genus-paper, or by devoting each larger paper to a species, adding in future other varieties, and enclosing all the species-papers of the same genus within a folded sheet, on which the name of the genus is written.

We have adopted, for our own herbarium, the “foolscap” size. A sheet of paper receives within its fold the specimens of a single species; these are affixed to the right-hand page, when the sheet is open, and a small envelope is attached by its face to the same page at the bottom, in which loose specimens are kept for minute and special examination, or as duplicates. When the sheet is folded, the specific name is written at the right-hand lower corner, or, what is better, a strip containing that name and its number is cut from a copy of the “Index Fungorum,” kept for the purpose, and gummed in its place. The remainder of this page, which is of white cartridge paper, is occupied with memoranda referring to the species enclosed, sketches of the spores, synonyms, references to descriptions, &c. All the species-papers of each genus are placed together within a sheet of brown paper, half an inch larger in each direction, with the name of the genus written at the left-hand corner. A piece of millboard, the size of the covers when folded, separates each order.

When a leaf, or other portion of a plant, is to be examined under the microscope, with the view of determining the genus and species of its parasite, it may be fastened with small pins to a piece of sheet cork, two or three inches square, and about one-eighth of an inch in thickness, such as used for lining entomological cabinets, and so placed under a lens that it may easily be brought into focus, and both hands left at liberty; or a dissecting microscope may be used for the purpose. From one of the pustules the spores may be removed on the sharp point of a penknife, and placed in a drop of water on a glass slide. A thin glass cover is placed over the drop of water, and the slide is submitted to examination. For further satisfaction it will often be found necessary to make carefully a thin section of a pustule, and place this under the microscope, a more troublesome but also much more satisfactory method. Reference to the Appendix will soon determine the name and position of the fungus, provided it belongs to the section to which this volume is devoted.

If it is thought desirable to mount the spores as permanent objects, there is no obstacle to such a proceeding. The spores of the different species of Aregma, of Triphragmium, and many of the PucciniÆ, will be worth the trouble. We have tried several media, and only adopted Glycerine or Balsam; either of these, especially the former, if the greater difficulty of securely closing can be overcome, will answer the purpose.

It should be remarked that in the examination of moulds, such as those of the genus Peronospora, included in this work, if any fluid be added, the acrospores are immediately disconnected from the threads, and float in the medium; so that if their mode of attachment or arrangement would be studied, that must be achieved without the addition of any fluid whatever.

The best methods of observing germination, the production of zoospores, &c., have been detailed already.

Thus do we arrive at the close of the task which we had set ourselves to perform. This fragment of a history of microscopic fungi goes forth to plead for students, and prepare the path for somewhat more complete. Is it not a shame that more than two thousand species of plants (never mind how minute, how insignificant) should be known to exist, and constitute a flora, in a nation amongst the foremost in civilization, and yet be without a complete record? It is nevertheless true that hundreds of minute organisms, exquisite in form, marvellous in structure, mysterious in development, injurious to some, linked with the existence of all, are known to flourish in Britain without a history or description, in the language of, or produced in, the country they inhabit. It is also true that the descriptions, by which they should be known, of hundreds of the rest lie buried in a floating literature whence the youthful and ardent student needs, not only youth and ardour, but leisure and perseverance unlimited to unearth them. This, however, by the way; we may be too great dotards on our native land, and foolish in our desire to see her in advance, and not in the rear in scientific attainments, pursuits, and productions of other and, perhaps, less favoured nations.

Already we fear that some of our readers will have thought our story of rust, brand, and mildew interminable, and looked anxiously for the close. On the other hand, we would flatter ourselves into the belief that some have made a new acquaintance with these minute and mysterious forms, and would fain know more. The groups of fungi which we have endeavoured to illustrate have, with but few exceptions, one feature in common, i.e., that they are parasitic on living plants. These constitute but a small portion of the microscopical species found in this country. To the elegant forms of mould which inhabit decaying vegetable substances no allusion has been made. These constitute a fairy flora of forests and gardens with features as varied, and fruits as multiform, as those of the trees and flowers of the earth. The numerous, and often marvellous, phases of low life developed upon dead leaves and rotten sticks, would in description occupy a far greater space than we have devoted to our subject. Yet, for all these, we have not spared so much as a passing word. The treasures still left unopened are far richer than even those we have revealed. The gates of another world have been thrown open, but we have scarcely passed the threshold. A minutely and elaborately illuminated page of the book of Nature has been turned, and we have only perused a single line. We might traverse the primeval forests of the new world, and explore the unknown regions of the old, and not encounter so much to excite our admiration, or cause our wonder, as lies about our feet at home; marvels which we tread beneath our feet, or kick from our path, because they appear to be only rotten sticks, withered grass, and decaying leaves. All this may appear as the dream of an enthusiast, or the ravings of one on whom the moon has shone too often. When Columbus spoke of a new world beyond the seas, which he longed to seek and explore, some believed him duped, and others called him mad. We write of no chimerical El Dorado, we speak of no undiscovered world, and yet we seem to allude to wonders still unknown, because so few have had the courage to venture upon the journey for themselves.

In sober earnestness, however, let us commend this pursuit to all who possess a microscope and leisure to use it. It may be for a time the “pursuit of knowledge under difficulties,” on account of the condition of our literature on this special subject; but many workers will produce more readers, and good books will come when there are more to purchase and appreciate. It is not improbable that in more cases than have come under our own observation, microscopists wearied of diatoms and allied forms, or deeming themselves in possession of all that is novel or interesting in this direction, are seeking for a new field of labour, and a new subject to kindle up a new enthusiasm. To these we have advised, and to any more such we continue to advise, that fungi should have a fair trial. If variety is desired, here they will have at least 2,000 species for a knowledge of which the microscope is essential. If they thirst for discovery, let them be assured that here also the earnest worker is sure to meet with such a reward. Or if they would acquaint themselves with the manifestations of Divine power as developed in the most minute of created things, let them follow such observers as Tulasne and De Bary, and seek the “why and the wherefore” of the phenomena of mycetal life.

If there should still be any hesitation whether there is in this pursuit sufficient of the element of variety, for those who do not desire to pursue the subject into its deepest scientific recesses, to render it available for them, let them go to a good public library, such as that of the British Museum, and inquire for the large illustrated work by Corda, entitled “Icones Fungorum,” or the more recent volumes by Tulasne (Selecta Fungorum Carpologia), and examine the figures of microscopic fungi in either of those works, and decide for themselves.