Popular History of Lichens.
Chapter I. History of lichenology.

A Popular History of British Lichens, comprising an account of their structure, reproduction, uses, distribution and classification. By W. Lauder Lindsay, M.D., Fellow of the Botanical and Royal Physical Societies of Edinburgh, etc. Lovell Reeve, 5, Henrietta Street, Covent Garden. Lontoo 1856.

(Tekstiin lisätty kappaleita lukemisen helpottamiseksi. // Some paragraphs added to the original text for making reading easier.)

"Let me suggest that the study of the simple plants ought to take the precedence of those whose organization is more complex and intricate, as being the simplest expression of the laws of vegetable life."—Cotltas.
The dark and almost impenetrable veil which has for ages enveloped the subject of Lichenology,—and especially the question of the reproduction of Lichens,—has not been due to the deficiency or absence of a special literature. On the contrary, the Lichens, like the Salices and Hieracia, may be said in a manner to have been "rendered botanically odious by books." In the works of the earlier Lichenologists,— who did not possess suitable instruments for research,—the microscope in particular having been rendered available in botanical science only within a comparatively recent period,—speculation to a great extent took the place of fact; there was profitless straining after analogies which did not really exist, — a bending of fact to the subservience of theory. Observations were imperfectly made, or were coloured and perverted by the dominant idea. Fruitless discussions were entered into on the reproductive functions, based on erroneous or imperfect data: each author built up a new classification and devised a new nomenclature. As a necessary consequence, genera and species have been in a constant state of transition, both as regards name and position in classification.

Some Lichenologists, whose dominant tendency has been the splitting up of species, and the devising of new names, have been constantly creating new subdivisions of the family, new genera, new species, and new varieties, thus adding materially to the complexity of nomen clature and classification; others, whose minds led them to generalize, have, on the other hand, been as actively employed in fusing together or combining certain genera and destroying others, thus contributing towards a simplification of the natural history of the Lichens.

Such a condition of Lichenology could not fail to render its study both difficult and repulsive to the general student of natural science; —hence one great cause, undoubtedly, of the obscurity in which it has hitherto remained, of the neglect which it has hitherto suffered. Instead of advancing science, the labours of earlier Lichenologists more frequently constituted barriers to its progress, for later authors have been chiefly occupied in correcting the errors, supplying the omissions, and clearing from the field the "Rudis indigestaque moles" of crude theories accumulated by their predecessors. Thus, though much has been written, little real progress has been made until within a comparatively recent period. We may now be said to be entering on a new era in Lichenology; it is now being studied in a more philosophic spirit, and with all the aids which modern discoveries in science— which the microscope and chemistry—can furnish.

Facts are being earnestly and patiently sought after; generaliza tion and theory avoided until a sufficiency of data be accumulated to form a firm foundation for the superstructure of classification; and a determination is being evinced to overcome all the obstacles and difficulties which naturally beset a subject which has been rendered so intricate, and which is now being stormed as a fortress that has successfully withstood the repeated assaults of scientific observers; and moreover we believe the labourers are increasing and volunteers are coming forward who esteem it an honour to join this forlorn hope of Cryptogamic Botany, who are eager for the work solely on account of its difficulty. In propor tion as the Lichens are more fully studied by the reflected light of modern science,—and especially in proportion as their various forms or phases, produced or modified by variations in external circumstances, are carefully examined in different countries and under different climes,—so will the study of Lichenology become more simple and attractive. It will not suffice to collate the characters of species contained in the musty folios of celebrated Herbaria; nor is it enough to apply the microscope and chemical reagents to the examination of old and dried specimens.

Of observers of this class we have had enough. But the labours of the student must equally begin and terminate on the spot where the Lichens grow; his herbarium and book of reference must be the hill, the heath, the forest; there he must watch patiently and note accurately—it may be for a series of years—the stages of origin, growth, and decay of species under all the influences, terrestrial and aerial, by which these are so liable to be affected.

Several Lichens were probably known to the ancients as furnishing valuable purple dyes, and appear to be alluded to under various names in the works of Dioscorides, Theophrastus, and Pliny; but they do not appear to have attracted much scientific attention, or to have become the subjects of special classification till about the beginning of the seventeenth century. The ideas of the earlier authors, even for a considerable time subsequent to this period, regarding their nature and position in the scale of vegetation, were of a very primitive and erroneous kind. Many species were believed to be accidental or anomalous productions, developed according to no known law,—growing under conditions inimical to all other vegetation: hence the theory of equivocal or spontaneous generation was advanced in explanation of their origin and growth.

One phasis of this theory appeared in the doctrine that, according to the external circumstances by which they are surrounded in germination or genesis,—according as the medium in which they arise and vegetate is earth, water, or decaying organic matter,—certain vegetable cellules become Lichens, Algae, or Fungi; nay, some authors have even gone the length of asserting, that under certain circumstances they are transmutable into animalcules!

Another phase assumed the form of a belief that the decomposition of organic bodies gives origin to organic bodies lower in the scale of being, and that the Lichens are merely the result of the decom position of a higher vegetation. Such ideas, which may be regarded as foreshadows of, or as analogous to, the progressive-development theories of more modern times, how ever ingenious in themselves and attractive from their apparent simplicity, could not for a moment stand the test of experience. They originated in, and were fostered by, the speculative dispositions of the German school of observers. Sprengel, who very beautifully designates the Cryptogamia as the "secret recesses of Nature's sanctuary," speaks of many of the Lichens as "formed of nothing but pure precipitation from the vegetable juices, except here and there some slight rudiments of a cellular organization."

In reviewing briefly the onward progress or history of Lichenology in Europe, we may regard it as divisible into three eras, the first dating about the year 1700, and marked by the labours of Tournefort; the second occurring about the year 1800, and characterized by the voluminous and valuable works of Acharius; and the third commencing about 1850, and distinguished by the important monograph of Tulasne. Prior to the date of the first era above alluded to, the Lichens were included indiscriminately, under various names, among Mosses or Fungi. By Tournefort, in his 'Institutiones Rei Herbariæ' they were for the first time collected into a separate group, to which he gave the term Lichen.

This term, though its derivation has been given variously by different authors, is probably derived from the Greek word [--], leichen or lichen, a wart, which the fructification of this group of plants frequently resembles. This group, or family, Lichen, did not however include all the genera or species of the family as now known; certain of them, having a rigid or somewhat coral-like consistence or appearance, he dissociated under the name Coralloides, a group in which he included also some sections of the Fungus or Mushroom family. About forty years subsequently Dillenius, in his classic 'Historia Muscorum,' further subdivided the family by constituting his sections Usnea, Coralloides, and Lichenoides; with these however were associated certain sections of cognate cryptogamic families, in this case the Hepaticæ and Conservæ.

The illustrious Linnaeus preferred embracing all the Lichens under a single genus, Lichen, which he how ever subdivided into eight sections, according to the characters of the vegetative system, or thallus. Upon the latter, up to this period, Lichenologists had based their classification and nomenclature; but Hedwig and Gaertner, whose works are next in order of date, carefully examined the fructification of Lichens, and upon their characters, real or supposed, they based rival theories of their reproduction. This subject has been, until within the last few years, the pons asinorum of Lichenologists, and without suitable means of research, it could not fail to be a botanical problem of insuperable difficulty.

The absence of fact, however, did not prevent the development of theory; and for a considerable period there raged in the botanical world a discussionary war as to the most probable physiology of reproduction in Lichens. One faction of disputants, whose motto was probably "omne vivum ex ovo," and who believed with Linnaeus,

"Vegetabile omne flore et fructu instruitur,
at nulla species bis destituta,"
contended, on the ground of analogy, for the necessary sexuality of organs; and various authors endowed various bodies, seated on the surface of the thallus, with the male or complementary functions.

The opposite faction, on the ground of observation, denied the proof of the existence of either male or female organs of any kind, and asserted that Lichens were invariably propagated by means of isolated cellules which were analagous, in regard to function, to the buds, or propagos (offshoots) of the higher plants. Between these extreme views, numerous theories were from time to time advanced to account for their discrepancies, or supply their omissions; but they were all equally characterized by one circumstance, which completely invalidated their sta bility, viz. that they were unsupported by, or inconsistent with fact.

According to the views taken by observers of the relative importance of the vegetative or reproductive organs, systems of classification were based on the characters of the thallus or apothecia; and as a result in either case, they were unnatural and artificial. By earlier Lichenologists, the characters of the thallus alone were taken as a basis of classification; by their immediate successors, those of the apothecia; but later observers have discovered that their only safe rule of guidance is "In medio tutissimus ibis." By taking the characters of the thallus as a base, we are compelled to group together Lichens having the most opposite fructification; while by assuming those of the apothecium we place side by side species possessed of the most dissimilar vegetative systems: in either case the harmony of nature is offended by the unnatural combination.

It is only by regarding together the vegetative and reproductive systems,—their minute or microscopic anatomy, as well as their general or external characters, physical and chemical,—that we can hope to succeed in founding a natural system of classification, consisting of a chain of natural groupings or small families, not only more or less closely allied to each other but to other Cryptogamic families, especially the Algse on the one hand and Fungi on the other. Such a system has hitherto been a desideratum in Lichenology, a want which could not, until the invention of the microscope, have been supplied; such a system has not yet been attained, though the labours of recent investigators in Germany, France, and England, have contributed much in this direction.

One of the first attempts at a natural system, composed of Natural Orders or sections, was made by Hoffmann at Gottingen, towards the close of the era which we have been describing. The advent of the second era was marked by the works of a distinguished Swede, Eric Acharius, works which gave an impetus to the study of Lichenology, and which have, to a greater or less extent, formed the basis of all subsequent lichenological literature. But these works were too much mere systems of classification,—mere catalogues of names and lists of specific characters: there is a deficiency of information regarding minute anatomy. The same remark is applicable to the 'Lichenographia Europsea Reformata' of Fries [of date 1831], and the 'Enumeratio Critica Lichenum Europaeorum' of Schaarer [published so lately as 1850],—the most valuable works for a description of European Genera and Species to which we can refer the student.

It is only within the last few years that the minute anatomy and physico-chemical characters of the vegetative and reproductive cell-systems of the Lichens have attracted the attention of botanical microscopists. In Germany, a host of monographers, such as Itzigsohn, Bayrhoffer, Rabenhorst, Von Flotow, and Von Holle; in France, Tulasne and Montague; in Russia, Buhse; and in England Leighton, have recently published valuable contributions to this branch of Lichenology,—contributions which have placed the Lichens, in point of anatomy and physiology, on at least an equal footing with other Cryptogamic families, to which they have hitherto been considered far inferior in the scale of vegetation.

But the most important monograph ever published on this subject is unquestionably that of Tulasne,—his 'Memoire pour servir a l'Histoire Organographique et Physiologique des Lichens' published in the 'Annales des Sciences Naturelles' in 1852. This author apparently sets at rest the long debated question of the reproduction of Lichens, by describing the minute anatomy of organs which must now be generally considered to be endowed with a function complementary to that of the apothecia, or female organs, so long familiar to Lichenologists. Considerable facility has likewise been given of late years to the study of Lichenology by the publication of fasciculi of dried species, classified and named, by Desmazieres in France, Schasrer in Switzerland, Fries in Sweden, Flcerke, Flotow, Zwack, and others, in Germany, Massolongo in Italy, Leighton and Bohler in Britain.

Lichenology has never found much favour in Britain; comparatively few monographs have been devoted to the subject—more particularly to the minute anatomy of native species—and the descriptions and arrangement of British Lichens, to be found in several general or special floras of our country, are based on those laid down by Acharius fifty years ago.

The chief works to which reference may be made for descriptions of British species are the classic 'English Botany' of Sowerby, originally published a century ago, which contains figures and short descriptions of the greater number of British Lichens, arranged however without any system; the elaborate but fragmentary and unfinished 'Lichenographia Britannica' of Turner and Borrer; the 'English Flora' of Sir J. E. Smith; the 'Flora Scotica' of Sir W. Hooker; the 'Flora Scotica' of Light foot; the 'Flora Edinensis' of Greville, one of the first of British cryptogamists; the 'Flora Hibemica' of Mackay; and the monographs on the British Angiocarpous Lichens and on the British Graphideæ, lately published by Leighton. The works of the latter author have the merit of being the first British works to contain descriptions of the spores of native species; his monograph on the Angiocarpi is indeed based upon or "elucidated by their sporidia." The ground has thus been broken in Britain for a more philosophic study of Lichenology than heretofore; but much remains to be accomplished,—the field is open, the harvest promises to be bountiful.

Nor must we here omit to mention the labours of our facilè botanicorum princeps, Robert Brown, in the description of Arctic species collected in the voyages of Parry and Scoresby; or of Churchill Babington in the lichenographical department of the magnificent floras of New Zealand, the Antarctic regions, etc., recently published by Dr. J. D. Hooker, the distinguished son of a distinguished sire. North American Lichens have been described by Halsey, Torrey, and Tuckerman; those of Chili by Nylander; those of Brazil by Eschweiler; and the collection and description of species from other and more distant parts of the world, within the last few years, serve to corroborate the belief and justify the anticipation that the present era of Lichenology is much more promising of valuable results to Botanical Science than any of its predecessors.

-Dioscorides, ed. Sarracenii, 1598:
Theophrastus, Hist. Plantarum, ed. Heinsii, 1613:
Pliny, Nat. Hist., ed. Valpy:
Ray, Hist. Plantarum:
Hudson, Kloia Anglica:
Micheli, Nova Plantarum Genera, 1729: Hedwig, Theoria Generationis et Fructificationis Plantarum Cryptogam. Linnaei, 1798:
Hill, Hist. of Plants:
Luyken, Tentamen Historiae Lichenum in genere:
Abbe Wulfen, Description of Lichens:
Sir W. Watson, on a genus of plant called Lichen: Dickson, Fasciculi tres Plantarum Cryptog. Britanniae:
Hoffmann, Dissertatio et Adumbratio Plantarum e classe Cryptogamiae Linnaei quae Lichenes dicuntur:
Loudon, Encyclopaedia of Plants:
Edinburgh Encyclopaedia, Art. Lichens:
Kützing, 'Die Unwandlung niederer Algenformen in hohere so wie auch in Gattungen ganz verschiedener Familien und Classen hoherer Cryptogamen mit zelligem Bau,' contained in the 'Naturnkundige Verhandelingen van de Hollandsche Maatschappij der Wetenschappen te Haarlem.'

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