THE INTERNATIONAL SCIENTIFIC SERIES.

VOLUME XV.



THE INTERNATIONAL SCIENTIFIC SERIES.

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XIV. THE CHEMISTRY OF LIGHT AND PHOTOGRAPHY; in its Application to Art, Science, and Industry. By Dr. Hermann Vogel. One Hundred Illustrations. (In press.)

XV. FUNGI; their Nature, Influence, and Uses. By M. C. Cooke, M.A., LL.D. Edited by Rev. M. J. Berkeley, M.A., F.L.S. With 109 Illustrations. (In press.)

XVI. OPTICS. By Professor Lommel, University of Erlangen. (In press.)



THE INTERNATIONAL SCIENTIFIC SERIES.



FUNGI:

THEIR

NATURE AND USES.

BY M. C. COOKE, M.A., LL.D.

EDITED BY THE REV. M. J. BERKELEY, M.A., F.L.S.



NEW YORK: D. APPLETON AND COMPANY, 549 AND 551 BROADWAY. 1875.



PREFACE BY THE EDITOR.

As my name appears on the title-page of this volume, it is necessary that I should exactly state what part I had in its preparation. I had no doubt originally engaged to undertake the work myself; but finding, from multiplicity of engagements and my uncertain health, that I could not accomplish it satisfactorily, I thought the best course I could take was to recommend Mr. Cooke to the publishers; a gentleman well known, not only in this country, but in the United States. The whole of the work has therefore been prepared by himself, the manuscript and proof sheets being submitted to me from time to time, in which I merely suggested such additions as seemed needful, subjoining occasionally a few notes. As the work is intended for students, the author has had no hesitation in repeating what has been stated in former chapters where it has been thought to prove useful. I have no doubt that the same high character will justly apply to this as to Mr. Cooke's former publications, and especially to his "Handbook of British Fungi."

M. J. BERKELEY.

SIBBERTOFT,

November 23, 1874.



CONTENTS.

PAGE I. NATURE OF FUNGI. 1 II. STRUCTURE. 17 III CLASSIFICATION 64 IV. USES. 82 V. NOTABLE PHENOMENA. 105 VI. THE SPORE AND ITS DISSEMINATION. 119 VII. GERMINATION AND GROWTH. 137 VIII. SEXUAL REPRODUCTION. 163 IX. POLYMORPHISM. 182 X. INFLUENCES AND EFFECTS. 209 XI. HABITATS. 233 XII. CULTIVATION. 253 XIII. GEOGRAPHICAL DISTRIBUTION. 266 XIV. COLLECTION AND PRESERVATION. 287 INDEX. 295



LIST OF ILLUSTRATIONS.

FIG. PAGE 1. Agaric in Process of Growth. 17 2. Section of Common Mushroom. 21 3. Sterile cells, Basidia, Cystidium, from Gomphidius. 21 4. Polyporus giganteus (reduced). 23 5. Hydnum repandum. 24 6. Calocera viscosa. 24 7. Tremella mesenterica. 24 8. Basidia and spores of Phallus. 28 9. Basidia and spores of Lycoperdon. 29 10. Threads of Trichia. 31 11. Arcyria incarnata, with portion of threads and spore. 33 12. Diachaea elegans. 34 13. Cyathus vernicosus. 34 14. Cyathus, Sporangia and spores. 35 15. Asterosporium Hoffmanni. 36 16. Barren Cysts and Pseudospores of Lecythea. 36 17. Coleosporium Tussilaginis. 36 18. Melampsora salicina, pseudospores of 36 19. Cystopus candidus, conidia of 38 20. Xenodochus carbonarius, pseudospore. 38 21. Phragmidium bulbosum, pseudospores. 38 22. Pseudospores of Puccinia. 40 23. Thecaphora hyalina, pseudospores. 41 24. AEcidium Berberidis, peridia of 41 25. Helminthosporium molle, threads and spores. 42 26. Acrothecium simplex. 44 27. Peronospora Arenariae. 44 28. Polyactis cinerea. 47 29. Peziza Fuckeliana, with ascus and sporidia. 47 30. Penicillium chartarum. 50 31. Mucor mucedo, with sporangia. 50 32. Small portion of Botrytis Jonesii. 54 33. Section of cup of Ascobolus. 57 34. Asci, sporidia, and paraphyses of Ascobolus. 59 35. Perithecium of Sphaeria. 61 36. Uncinula adunca, conceptacle with appendages. 62 37. Agaricus nudus. 66 38. Scleroderma vulgare, Fr. 69 39. Ceuthospora phacidioides. 69 40. Rhopalomyces candidus. 74 41. Mucor caninus. 75 42. Sphaeria aquila, cluster of perithecia. 78 43. Morchella gigaspora, from Kashmir. 99 44. Cyttaria Gunnii 101 45. Spores of Agarics 121 46. Spores of Lactarius 121 46a. Spores of Gomphidius 122 47. Spores of Polyporus, Boletus, and Hydnum. 122 48. Diachea elegans, capellitium of 123 49. Spore of Hendersonia polycystis. 126 50. Spores of Dilophospora graminis. 126 51. Spores of Discosia. 126 52. Spore of Prosthemium betulinum. 126 53. Spore of Stegonosporium cellulosum. 126 54. Stylospores of Coryneum disciforme. 126 55. Spores of Asterosporium Hoffmanni. 126 56. Spores of Pestalozzia. 126 57. Bispora monilioides, concatenate spores 126 58. Pseudospores of Thecaphora hyalina. 128 59. Pseudospores of Puccinia. 128 60. Pseudospores of Triphragmium. 128 61. Pseudospores of Phragmidium bulbosum. 128 62. Winter spores of Melampsora salicina. 128 63. Spores of Helicocoryne. 129 64. Sporidium of Genea verrucosa. 130 65. Alveolate sporidium of Tuber. 130 66. Asci, sporidia, and paraphyses of Ascobolus. 131 67. Sporidium of Ostreichnion Americanum. 132 68. Ascus and sporidia of Hypocrea. 135 69. Sporidium of Sphaeria ulnaspora. 135 70. Sporidia of Valsa profusa. 135 71. Sporidia of Massaria foedans. 135 72. Sporidium of Melanconis bicornis. 135 73. Caudate sporidia of Sphaeria fimiseda. 135 74. Sporidia of Valsa thelebola. 135 75. Sporidia of Valsa taleola. 135 76. Sporidium of Sporormia intermedia. 135 77. Asci and sporidia of Sphaeria (Pleospora) herbarum. 135 78. Sporidium of Sphaeria putaminum. 135 79. Basidia and spores of Exidia spiculosa. 139 80. Germinating spore and corpuscles of Dacrymyces. 140 81. Germination of AEcidium Euphorbia. 142 82. Germinating pseudospores of Coleosporium Sonchi. 144 83. Germinating pseudospore of Melampsora betulina. 144 84. Germinating pseudospore of Uromyce appendiculatus. 145 85. Germinating pseudospore of Puccinia Moliniae. 146 86. Germinating pseudospore of Triphragmium Ulmariae. 146 87. Germinating pseudospore of Phragmidium bulbosum. 147 88. Germinating pseudospores of Podisoma Juniperi. 149 89. Germinating pseudospore of Tilletia caries. 150 90. Pseudospore of Ustilago receptaculorum in germination, and secondary spores in conjugation. 151 91. Conidia and zoospores of Cystopus candidus. 151 92. Resting spore of Cystopus candidus with zoospores. 152 93. Zygospores of Mucor phycomyces. 158 94. Sporidium of Ascobolus germinating. 161 95. Zygospore of Mucor. 164 96. Zygospore of Rhizopus in different stages. 166 97. Conjugation in Achlya racemosa. 169 98. Conjugation in Peronospora. 171 99. Antheridia and oogonium of Peronospora. 172 100. Conjugation in Peziza omphalodes. 176 100a. Formation of conceptacle in Erysiphe. 176 101. Tilletia caries with conjugating cells. 178 102. Aspergillus glaucus and Eurotium. 190 103. Erysiphe cichoracearum, receptacle and mycelium. 192 104. Twig with Tubercularia and Nectria. 193 105. Section of Tubercularia with conidia. 193 106. D. Nectria with Tubercularia, ascus and paraphyses. 195 107. Cells and pseudospores of AEcidium berberidis. 201 108. Cells and pseudospores of AEcidium graveolens. 201 109. Torrubia militaris on pupa of a moth. 243



FUNGI

THEIR NATURE, USES, INFLUENCES, ETC.



I.

NATURE OF FUNGI.

The most casual observer of Nature recognizes in almost every instance that comes under his notice in every-day life, without the aid of logical definition, the broad distinctions between an animal, a plant, and a stone. To him, the old definition that an animal is possessed of life and locomotion, a plant of life without locomotion, and a mineral deficient in both, seems to be sufficient, until some day he travels beyond the circuit of diurnal routine, and encounters a sponge or a zoophyte, which possesses only one of his supposed attributes of animal life, but which he is assured is nevertheless a member of the animal kingdom. Such an encounter usually perplexes the neophyte at first, but rather than confess his generalizations to have been too gross, he will tenaciously contend that the sponge must be a plant, until the evidence produced is so strong that he is compelled to desert his position, and seek refuge in the declaration that one kingdom runs into the other so imperceptibly that no line of demarcation can be drawn between them. Between these two extremes of broad distinction, and no distinction, lies the ground occupied by the scientific student, who, whilst admitting that logical definition fails in assigning briefly and tersely the bounds of the three kingdoms, contends that such limits exist so positively, that the universal scientific mind accepts the recognized limit without controversy or contradiction.

In like manner, if one kingdom be made the subject of inquiry, the same difficulties will arise. A flowering plant, as represented by a rose or a lily, will be recognized as distinct from a fern, a seaweed, or a fungus. Yet there are some flowering plants which, at first sight, and without examination, simulate cryptogams, as, for example, many Balanophorae, which the unscientific would at once class with fungi. It is nevertheless true that even the incipient botanist will accurately separate the phanerogams from the cryptogams, and by means of a little more, but still elementary knowledge, distribute the latter amongst ferns, mosses, fungi, lichens, and algae, with comparatively few exceptions. It is true that between fungi and lichens there exists so close an affinity that difficulties arise, and doubts, and disputations, regarding certain small groups or a few species; but these are the exception, and not the rule. Botanists generally are agreed in recognizing the five principal groups of Cryptogamia, as natural and distinct. In proportion as we advance from comparison of members of the three kingdoms, through that of the primary groups in one kingdom, to a comparison of tribes, alliances, and orders, we shall require closer observation, and more and more education of the eye to see, and the mind to appreciate, relationships and distinctions.

We have already assumed that fungi are duly and universally admitted, as plants, into the vegetable kingdom. But of this fact some have even ventured to doubt. This doubt, however, has been confined to one order of fungi, except, perhaps, amongst the most illiterate, although now the animal nature of the Myxogastres has scarcely a serious advocate left. In this order the early condition of the plant is pulpy and gelatinous, and consists of a substance more allied to sarcode than cellulose. De Bary insinuated affinities with Amoeba,[A] whilst Tulasne affirmed that the outer coat in some of these productions contained so much carbonate of lime that strong effervescence took place on the application of sulphuric acid. Dr. Henry Carter is well known as an old and experienced worker amongst amoeboid forms of animal life, and, when in Bombay, he devoted himself to the examination of the Myxogastres in their early stage, and the result of his examinations has been a firm conviction that there is no relationship whatever between the Myxogastres and the lower forms of animal life. De Bary has himself very much modified, if not wholly abandoned, the views once propounded by him on this subject. When mature, and the dusty spores, mixed with threads, sometimes spiral, are produced, the Myxogastres are so evidently close allies of the Lycoperdons, or Puffballs, as to leave no doubt of their affinities. It is scarcely necessary to remark that the presence of zoospores is no proof of animal nature, for not only do they occur in the white rust (Cystopus), and in such moulds as Peronospora,[B] but are common in algae, the vegetable nature of which has never been disputed.

There is another equally important, but more complicated subject to which we must allude in this connection. This is the probability of minute fungi being developed without the intervention of germs, from certain solutions. The observations of M. Trecul, in a paper laid before the French Academy, have thus been summarized:—1. Yeast cells may be formed in the must of beer without spores being previously sown. 2. Cells of the same form as those of yeast, but with different contents, arise spontaneously in simple solution of sugar, or to which a little tartrate of ammonia has been added, and these cells are capable of producing fermentation in certain liquids under favourable conditions. 3. The cells thus formed produce Penicillium like the cells of yeast. 4. On the other hand, the spores of Penicillium are capable of being transformed into yeast.[C] The interpretation of this is, that the mould Penicillium may be produced from a sugar solution by "spontaneous generation," and without spore or germ of any kind. The theory is, that a molecular mass which is developed in certain solutions or infusions, may, under the influence of different circumstances, produce either animalcules or fungi. "In all these cases, no kind of animalcule or fungus is ever seen to originate from preexisting cells or larger bodies, but always from molecules."[D] The molecules are said to form small masses, which soon melt together to constitute a globular body, from which a process juts out on one side. These are the so-called Torulae,[E] which give off buds which are soon transformed into jointed tubes of various diameters, terminating in rows of sporules, Penicillium, or capsules containing numerous globular seeds, Aspergillus (sic).

This is but another mode of stating the same thing as above referred to by M. Trecul, that certain cells, resembling yeast cells (Torula), are developed spontaneously, and that these ultimately pass through the form of mould called Penicillium to the more complex Mucor (which the writer evidently has confounded with Aspergillus, unless he alludes to the ascigerous form of Aspergillus, long known as Eurotium). From what is now known of the polymorphism of fungi, there would be little difficulty in believing that cells resembling yeast cells would develop into Penicillium, as they do in fact in what is called the "vinegar plant," and that the capsuliferous, or higher condition of this mould may be a Mucor, in which the sporules are produced in capsules. The difficulty arises earlier, in the supposed spontaneous origination of yeast cells from molecules, which result from the peculiar conditions of light, temperature, &c., in which certain solutions are placed. It would be impossible to review all the arguments, or tabulate all the experiments, which have been employed for and against this theory. It could not be passed over in silence, since it has been one of the stirring questions of the day. The great problem how to exclude all germs from the solutions experimented upon, and to keep them excluded, lies at the foundation of the theory. It must ever, as we think, be matter of doubt that all germs were not excluded or destroyed, rather than one of belief that forms known to be developed day by day from germs should under other conditions originate spontaneously.

Fungi are veritably and unmistakably plants, of a low organization, it is true, but still plants, developed from germs, somewhat analogous, but not wholly homologous, to the seeds of higher orders. The process of fertilization is still obscure, but facts are slowly and gradually accumulating, so that we may hope at some not very distant period to comprehend what as yet are little removed from hypotheses. Admitting that fungi are independent plants, much more complex in their relations and development than was formerly supposed, it will be expected that certain forms should be comparatively permanent, that is, that they should constitute good species. Here, also, efforts have been made to develop a theory that there are no legitimate species amongst fungi, accepting the terms as hitherto applied to flowering plants. In this, as in allied instances, too hasty generalizations have been based on a few isolated facts, without due comprehension of the true interpretation of such facts and phenomena. Polymorphism will hereafter receive special illustration, but meantime it may be well to state that, because some forms of fungi which have been described, and which have borne distinct names as autonomous species, are now proved to be only stages or conditions of other species, there is no reason for concluding that no forms are autonomous, or that fungi which appear and are developed in successive stages are not, in their entirety, good species. Instead, therefore, of insinuating that there are no good species, modern investigation tends rather to the establishment of good species, and the elimination of those that are spurious. It is chiefly amongst the microscopic species that polymorphism has been determined. In the larger and fleshy fungi nothing has been discovered which can shake our faith in the species described half a century, or more, ago. In the Agarics, for instance, the forms seem to be as permanent and as distinct as in the flowering plants. In fact, there is still no reason to dissent, except to a very limited extent, from what was written before polymorphism was accredited, that, "with a few exceptions only, it may without doubt be asserted that more certain species do not exist in any part of the organized world than amongst fungi. The same species constantly recur in the same places, and if kinds not hitherto detected present themselves, they are either such as are well known in other districts, or species which have been overlooked, and which are found on better experience to be widely diffused. There is nothing like chance about their characters or growth."[F]

The parasitism of numerous minute species on living and growing plants has its parallel even amongst phanerogams in the mistletoe and broom-rape and similar species. Amongst fungi a large number are thus parasitic, distorting, and in many cases ultimately destroying, their host, burrowing within the tissues, and causing rust and smut in corn and grasses, or even more destructive and injurious in such moulds as those of the potato disease and its allies. A still larger number of fungi are developed from decayed or decaying vegetable matter. These are found in winter on dead leaves, twigs, branches, rotten wood, the remains of herbaceous plants, and soil largely charged with disintegrated vegetables. As soon as a plant begins to decay it becomes the source of a new vegetation, which hastens its destruction, and a new cycle of life commences. In these instances, whether parasitic on living plants or developed on dead ones, the source is still vegetable. But this is not always the case, so that it cannot be predicated that fungi are wholly epiphytal. Some species are always found on animal matter, leather, horn, bone, &c., and same affect such unpromising substances as minerals, from which it would be supposed that no nourishment could be obtained, not only hard gravel stones, fragments of rock, but also metals, such as iron and lead, of which more may be said when we come to treat of the habitats of fungi. Although in general terms fungi may be described as "hysterophytal or epiphytal mycetals deriving nourishment by means of a mycelium from the matrix,"[G] there are exceptions to this rule with which the majority accord.

Of the fungi found on animal substances, none are more extraordinary than those species which attack insects. The white mould which in autumn proves so destructive to the common house-fly may for the present be omitted, as it is probably a condition of one of the Saprolegniei, which some authors include with fungi, and others with algae. Wasps, spiders, moths, and butterflies become enveloped in a kind of mould named Isaria, which constitutes the conidia of Torrubia, a genus of club-shaped Sphaeriae afterwards developed. Some species of Isaria and Torrubia also affect the larvae and pupae of moths and butterflies, converting the whole interior into a mass of mycelium, and fructifying in a clavate head. It has been subject for discussion whether in such instances the fungus commenced its development during the life of the insect, and thus hastened its death, or whether it resulted after death, and was subsequent to the commencement of decay.[H] The position in which certain large moths are found standing on leaves when infested with Isaria resembles so closely that of the house-fly when succumbing to Sporendonema Muscae, would lead to the conclusion that certainly in some cases the insect was attacked by the fungus whilst still living; whilst in the case of buried caterpillars, such as the New Zealand or British Hepialus, it is difficult to decide. Whether in life or death in these instances, it is clear that the silk-worm disease Muscardine attacks the living insect, and causes death. In the case of the Guepes vegetantes, the wasp is said to fly about with the fungus partially developed.

In all fungi we may recognize a vegetative and a reproductive system: sometimes the first only becomes developed, and then the fungus is imperfect, and sometimes the latter is far more prominent than the former. There is usually an agglomeration of delicate threads, either jointed or not, which are somewhat analogous to the roots of higher plants. These delicate threads permeate the tissues of plants attacked by parasitic fungi, or they run over dead leaves forming whitened patches, formerly bearing the name of Himantia, but really the mycelium of some species of Marasmius. If checked or disturbed, the process stops here, and only a mycelium of interwoven threads is produced. In this condition the mycelium of one species so much resembles that of another, that no accurate determination can be made. If the process goes on, this mycelium gives rise to the stem and cap of an agaricoid fungus, completing the vegetative system. This in turn gives origin to a spore-bearing surface, and ultimately the fruit is formed, and then the fungus is complete; no fungus can be regarded as perfect or complete without its reproductive system being developed. In some this is very simple, in others it is as complex. In many of the moulds we have miniature representatives of higher plants in the mycelium or roots, stem, branches, and at length capsules bearing sporidia, which correspond to seeds. It is true that leaves are absent, but these are sometimes compensated by lateral processes or abortive branchlets. A tuft of mould is in miniature a forest of trees. Although such a definition may be deemed more poetic than accurate, more figurative than literal, yet few could believe in the marvellous beauty of a tuft of mould if they never saw it as exhibited under the microscope. In such a condition no doubt could be entertained of its vegetable character. But there is a lower phase in which these plants are sometimes encountered; they may consist only of single cells, or strings of cells, or threads of simple structure floating in fluids. In such conditions only the vegetative system is probably developed, and that imperfectly, yet some have ventured to give names to isolated cells, or strings of cells, or threads of mycelium, which really in themselves possess none of the elements of correct classification—the vegetative system, even, being imperfect, and consequently the reproductive is absent. As already observed, no fungus is perfect without fruit of some kind, and the peculiarities of structure and development of fruit form one of the most important elements in classification. To attempt, therefore, to give names to such imperfect fragments of undeveloped plants is almost as absurd as to name a flowering plant from a stray fragment of a root-fibril accidentally cast out of the ground—nay, even worse, for identification would probably be easier. It is well to protest at all times against attempts to push science to the verge of absurdity; and such must be the verdict upon endeavours to determine positively such incomplete organisms as floating cells, or hyaline threads which may belong to any one of fifty species of moulds, or after all to an alga. This leads us to remark, in passing, that there are forms and conditions under which fungi may be found when, fructification being absent—that is, the vegetative system alone developed—they approximate so closely to algae that it is almost impossible to say to which group the organisms belong.

Finally, it is a great characteristic of fungi in general that they are very rapid in growth, and rapid in decay. In a night a puffball will grow prodigiously, and in the same short period a mass of paste may be covered with mould. In a few hours a gelatinous mass of Reticularia will pass into a bladder of dust, or a Coprinus will be dripping into decay. Remembering this, mycophagists will take note that a fleshy fungus which may be good eating at noon may undergo such changes in a few hours as to be anything but good eating at night. Many instances have been recorded of the rapidity of growth in fungi; it may also be accepted as an axiom that they are, in many instances, equally as rapid in decay.

The affinity between lichens and fungi has long been recognized to its full and legitimate extent by lichenologists and mycologists.[I] In the "Introduction to Cryptogamic Botany," it was proposed to unite them in one alliance, under the name of Mycetales, in the same manner as the late Dr. Lindley had united allied orders under alliances in his "Vegetable Kingdom;" but, beyond this, there was no predisposition towards the theory since propounded, and which, like all new theories, has collected a small but zealous circle of adherents. It will be necessary briefly to summarize this theory and the arguments by which it is supported and opposed, inasmuch as it is intimately connected with our subject.

As recently as 1868, Professor Schwendener first propounded his views,[J] and then briefly and vaguely, that all and every individual lichen was but an algal, which had collected about it a parasitic fungal growth, and that those peculiar bodies which, under the name of gonidia, were considered as special organs of lichens, were only imprisoned algae. In language which the Rev. J. M. Crombie[K] describes as "pictorial," this author gave the general conclusion at which he had arrived, as follows:—"As the result of my researches, all these growths are not simple plants, not individuals in the usual sense of the term; they are rather colonies, which consist of hundreds and thousands of individuals, of which, however, only one acts as master, while the others, in perpetual captivity, provide nourishment for themselves and their master. This master is a fungus of the order Ascomycetes, a parasite which is accustomed to live upon the work of others; its slaves are green algae, which it has sought out, or indeed caught hold of, and forced into its service. It surrounds them, as a spider does its prey, with a fibrous net of narrow meshes, which is gradually converted into an impenetrable covering. While, however, the spider sucks its prey and leaves it lying dead, the fungus incites the algae taken in its net to more rapid activity; nay, to more vigorous increase." This hypothesis, ushered upon the world with all the prestige of the Professor's name, was not long in meeting with adherents, and the cardinal points insisted upon were—1st. That the generic relationship of the coloured "gonidia" to the colourless filaments which compose the lichen thallus, had only been assumed, and not proved; 2nd. That the membrane of the gonidia was chemically different from the membrane of the other tissues, inasmuch as the first had a reaction corresponding to that of algae, whilst the second had that of fungi; 3rd. That the different forms and varieties of gonidia corresponded with parallel types of algae; 4th. That as the germination of the spore had not been followed further than the development of a hypothallus, it might be accounted for by the absence of the essential algal on which the new organism should become parasitic; 5th. That there is a striking correspondence between the development of the fruit in lichens and in some of the sporidiiferous fungi (Pyrenomycetes).

These five points have been combated incessantly by lichenologists, who would really be supposed by ordinary minds to be the most practically acquainted with the structure and development of these plants, in opposition to the theorists. It is a fact which should have some weight, that no lichenologist of repute has as yet accepted the theory. In 1873 Dr. E. Bornet[L] came to the aid of Schwendener, and almost exhausted the subject, but failed to convince either the practised lichenologist or mycologist. The two great points sought to be established are these, that what we call lichens are compound organisms, not simple, independent vegetable entities; and that this compound organism consists of unicellular algae, with a fungus parasitic upon them. The coloured gonidia which are found in the substance, or thallus of lichens, are the supposed algae; and the cellular structure which surrounds, encloses, and imprisons the gonidia is the parasitic fungus, which is parasitic on something infinitely smaller than itself, and which it entirely and absolutely isolates from all external influences.

Dr. Bornet believed himself to have established that every gonidium of a lichen may be referred to a species of algae, and that the connection between the hypha and gonidia is of such a nature as to exclude all possibility of the one organ being produced by the other. This he thinks is the only way in which it can be accounted for that the gonidia of diverse lichens should be almost identical.

Dr. Nylander, in referring to this hypothesis of an imprisoned algal,[M] writes: "The absurdity of such an hypothesis is evident from the very consideration that it cannot be the case that an organ (gonidia) should at the same time be a parasite on the body of which it exercises vital functions; for with equal propriety it might be contended that the liver or the spleen constitutes parasites of the mammiferae. Parasite existence is autonomous, living upon a foreign body, of which nature prohibits it from being at the same time an organ. This is an elementary axiom of general physiology. But observation directly made teaches that the green matter originally arises within the primary chlorophyll- or phycochrom-bearing cellule, and consequently is not intruded from any external quarter, nor arises in any way from any parasitism of any kind. The cellule at first is observed to be empty, and then, by the aid of secretion, green matter is gradually produced in the cavity and assumes a definite form. It can, therefore, be very easily and evidently demonstrated that the origin of green matter in lichens is entirely the same as in other plants." On another occasion, and in another place, the same eminent lichenologist remarks,[N] as to the supposed algoid nature of gonidia—"that such an unnatural existence as they would thus pass, enclosed in a prison and deprived of all autonomous liberty, is not at all consonant with the manner of existence of the other algae, and that it has no parallel in nature, for nothing physiologically analogous occurs anywhere else. Krempelhuber has argued that there are no conclusive reasons against the assumption that the lichen-gonidia may be self-developed organs of the lichen proper rather than algae, and that these gonidia can continue to vegetate separately, and so be mistaken for unicellular algae." In this Th. Fries seems substantially to concur. But there is one strong argument, or rather a repetition of an argument already cited, placed in a much stronger light, which is employed by Nylander in the following words:—"So far are what are called algae, according to the turbid hypothesis of Schwendener, from constituting true algae, that on the contrary it may be affirmed that they have a lichenose nature, whence it follows that these pseudo-algae are in a systematic arrangement to be referred rather to the lichens, and that the class of algae hitherto so vaguely limited should be circumscribed by new and truer limits."

As to another phase in this question, there are, as Krempelhuber remarks, species of lichens which in many countries do not fructify, and whose propagation can only be carried on by means of the soredia, and the hyphae of such could in themselves alone no more serve for propagation than the hyphae from the pileus or stalk of an Agaric, while it is highly improbable that they could acquire this faculty by interposition of a foreign algal. On the other hand he argues: "It is much more conformable to nature that the gonidia, as self-developed organs of the lichens, should, like the spores, enable the hyphae proceeding from them to propagate the individual."[O]

A case in point has been adduced[P] in which gonidia were produced by the hypha, and the genus Emericella,[Q] which is allied to Husseia in the Trichogastres, shows a structure in the stem exactly resembling Palmella botryoides of Greville, and to what occurs in Synalyssa. Emericella, with one or two other genera, must, however, be considered as connecting Trichogastres with lichens, and the question cannot be considered as satisfactorily decided till a series of experiments has been made on the germination of lichen spores and their relation to free algae considered identical with gonidia. Mr. Thwaites was the first to point out[R] the relation of the gonidia in the different sections of lichens to different types of supposed algae. The question cannot be settled by mere a priori notions. It is, perhaps, worthy of remark that in Chionyphe Carteri the threads grow over the cysts exactly as the hypha of lichens is represented as growing over the gonidia.

Recently, Dr. Thwaites has communicated his views on one phase of this controversy,[S] which will serve to illustrate the question as seen from the mycological side. As is well known, this writer has had considerable experience in the study of the anatomy and physiology of all the lower cryptogamia, and any suggestion of his on such a subject will at least commend itself to a patient consideration.

"According to our experience," he writes, "I think parasitic fungi invariably produce a sad effect upon the tissues they fix themselves upon or in. These tissues become pale in colour, and in every respect sickly in appearance. But who has ever seen the gonidia of lichens the worse for having the 'hypha' growing amongst them? These gonidia are always in the plumpest state, and with the freshest, healthiest colour possible. Cannot it enter into the heads of these most patient and excellent observers, that a cryptogamic plant may have two kinds of tissue growing side by side, without the necessity of one being parasitic upon the other, just as one of the higher plants may have half a dozen kinds of tissue making up its organization? The beautifully symmetrical growth of the same lichens has seemed to me a sufficient argument against one portion being parasitic upon another, but when we see all harmony and robust health, the idea that one portion is subsisting parasitically upon another appears to me to be a perfect absurdity."

It appears to us that a great deal of confusion and a large number of errors which creep into our modern generalizations and hypotheses, may be traced to the acceptance of analogies for identities. How many cases of mistaken identity has the improvement of microscopes revealed during the past quarter of a century. This should at least serve as a caution for the future.

Apart, however, from the "gonidia," whatever they may be, is the remainder of the lichen a genuine fungus? Nylander writes, "The anatomical filamentose elements of lichens are distinguished by various characters from the hyphae of fungi. They are firmer, elastic, and at once present themselves in the texture of lichens. On the other hand, the hyphae of fungi are very soft, they possess a thin wall, and are not at all gelatinous, while they are immediately dissolved by the application of hydrate of potash, &c."[T]

Our own experience is somewhat to the effect, that there are some few lichens which are doubtful as to whether they are fungi or lichens, but, in by far the majority of cases, there is not the slightest difficulty in determining, from the peculiar firmness and elasticity of the tissues, minute peculiarities which the practised hand can detect rather than describe, and even the general character of the fruit that they differ materially from, though closely allied to fungi. We have only experience to guide us in these matters, but that is something, and we have no experience in fungi of anything like a Cladonia, however much it may resemble a Torrubia or Clavaria. We have Pezizae with a subiculum in the section Tapesia, but the veriest tyro would not confound them with species of Parmelia. It is true that a great number of lichens, at first sight, and casually, resemble species of the Hysteriacei, but it is no less strange than true, that lichenologists and mycologists know their own sufficiently not to commit depredations on each other.

Contributions are daily being made to this controversy, and already the principal arguments on both sides have appeared in an English dress,[U] hence it will be unnecessary to repeat those which are modifications only of the views already stated, our own conclusions being capable of a very brief summary: that lichens and fungi are closely related the one to the other, but that they are not identical; that the "gonidia" of lichens are part of the lichen-organization, and consequently are not algae, or any introduced bodies; that there is no parasitism; and that the lichen thallus, exclusive of gonidia, is wholly unknown amongst fungi.

The Rev. J. M. Crombie has therefore our sympathies in the remark with which his summary of the gonidia controversy closes, in which he characterizes it as a "sensational romance of lichenology," of the "unnatural union between a captive algal damsel and a tyrant fungal master."

[A] De Bary, "Des Myxomycetes," in "Ann. des Sci. Nat." 4 ser. xi. p. 153; "Bot. Zeit." xvi. p. 357. De Bary's views are controverted by M. Wigand in "Ann. des Sci. Nat." 4 ser. (Bot.) xvi. p. 255, &c.

[B] De Bary, "Recherches sur le Developpement de quelques Champignons Parasites," in "Ann. des Sci. Nat." 4 ser. (Bot.) xx. p. 5.

[C] "Popular Science Review," vol. viii. p. 96.

[D] Dr. J. H. Bennett "On the Molecular Origin of Infusoria," p. 56.

[E] They have, however, no close relation with real Torulae, such as T. monilioides, &c.—COOKE'S Handbook, p. 477.

[F] Berkeley's "Outlines of British Fungology," p. 24.

[G] Berkeley's "Introduction to Cryptogamic Botany," p. 235.

[H] Gray, "Notices of Insects which form the Basis of Fungoid Parasites."

[I] On the relation or connection between fungi and lichens, H. C. Sorby has some pertinent remarks in his communication to the Royal Society on "Comparative Vegetable Chromatology" (Proceedings Royal Society, vol. xxi. 1873, p. 479), as one result of his spectroscopic examinations. He says, "Such being the relations between the organs of reproduction and the foliage, it is to some extent possible to understand the connection between parasitic plants like fungi, which do not derive their support from the constructive energy of their fronds, and those which are self-supporting and possess true fronds. In the highest classes of plants the flowers are connected with the leaves, more especially by means of xanthophyll and yellow xanthophyll, whereas in the case of lichens the apothecia contain very little, if any, of those substances, but a large amount of the lichenoxanthines so characteristic of the class. Looking upon fungi from this chromatological point of view, they bear something like the same relation to lichens that the petals of a leafless parasitic plant would bear to the foliage of one of normal character—that is to say, they are, as it were, the coloured organs of reproduction of parasitic plants of a type closely approaching that of lichens, which, of course, is in very close, if not in absolute agreement with the conclusions drawn by botanists from entirely different data."

[J] Schwendener, "Untersuchungen ueber den Flechtenthallus."

[K] Crombie (J. M.) "On the Lichen-Gonidia Question," in "Popular Science Review" for July, 1874.

[L] Bornet, (E.), "Recherches sur les Gonidies des Lichens," in "Ann. des Sci. Nat." 1873, 5 ser. vol. xvii.

[M] Nylander, "On the Algo-Lichen Hypothesis," &c., in "Grevillea," vol. ii. (1874), No. 22, p. 146.

[N] In Regensburg "Flora," 1870, p. 92.

[O] Rev. J. M. Crombie, in "Popular Science Review," July, 1874.

[P] Berkeley's "Introduction to Cryptogamic Botany," p. 373, fig. 78a.

[Q] Berkeley's "Introduction," p. 341, fig. 76.

[R] "Annals and Magazine of Natural History," April, 1849.

[S] In "Gardener's Chronicle" for 1873, p. 1341.

[T] "Grevillea," vol ii. p. 147, in note.

[U] W. Archer, in "Quart. Journ. Micr. Sci." vol. xiii. p. 217; vol. xiv. p. 115. Translation of Schwendener's "Nature of the Gonidia of Lichens," in same journal, vol. xiii. p. 235.



II.

STRUCTURE.

Without some knowledge of the structure of fungi, it is scarcely possible to comprehend the principles of classification, or to appreciate the curious phenomena of polymorphism. Yet there is so great a variety in the structure of the different groups, that this subject cannot be compressed within a few paragraphs, neither do we think that this would be desired if practicable, seeing that the anatomy and physiology of plants is, in itself, sufficiently important and interesting to warrant a rather extended and explicit survey. In order to impart as much practical utility as possible to this chapter, it seems advisable to treat some of the most important and typical orders and suborders separately, giving prominence to the features which are chiefly characteristic of those sections, following the order of systematists as much as possible, whilst endeavouring to render each section independent to a considerable extent, and complete in itself. Some groups naturally present more noteworthy features than others, and will consequently seem to receive more than their proportional share of attention, but this seeming inequality could scarcely have been avoided, inasmuch as hitherto some groups have been more closely investigated than others, are more intimately associated with other questions, or are more readily and satisfactorily examined under different aspects of their life-history.



AGARICINI.—For the structure that prevails in the order to which the mushroom belongs, an examination of that species will be almost sufficient. Here we shall at once recognize three distinct parts requiring elucidation, viz. the rooting slender fibres that traverse the soil, and termed the mycelium, or spawn, the stem and cap or pileus, which together constitute what is called the hymenophore, and the plates or gills on the under surface of the cap, which bear the hymenium. The earliest condition in which the mushroom can be recognized as a vegetable entity is in that of the "spawn" or mycelium, which is essentially an agglomeration of vegetating spores. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. At certain privileged points of the mycelium, the threads seem to be aggregated, and become centres of vertical extension. At first only a small nearly globose budding, like a grain of mustard seed, is visible, but this afterwards increases rapidly, and other similar buddings or swellings appear at the base.[A] These are the young hymenophore. As it pushes through the soil, it gradually loses its globose form, becomes more or less elongated, and in this condition a longitudinal section shows the position of the future gills in a pair of opposite crescent-shaped darker-coloured spots near the apex. The dermal membrane, or outer skin, seems to be continuous over the stem and the globose head. At present, there is no external evidence of an expanded pileus and gills; a longitudinal section at this stage shows that the gills are being developed, that the pileus is assuming its cap-like form, that the membrane stretching from the stem to the edge of the young pileus is separating from the edge of the gills, and forming a veil, which, in course of time, will separate below and leave the gills exposed. When, therefore, the mushroom has arrived almost at maturity, the pileus expands, and in this act the veil is torn away from the margin of the cap, and remains for a time like a collar around the stem. Fragments of the veil often remain attached to the margin of the pileus, and the collar adherent to the stem falls back, and thenceforth is known as the annulus or ring. We have in this stage the fully-developed hymenophore,—the stem with its ring, supporting an expanded cap or pileus, with gills on the under surface bearing the hymenium.[B] A longitudinal section cut through the pileus and down the stem, gives the best notion of the arrangement of the parts, and their relation to the whole. By this means it will be seen that the pileus is continuous with the stem, that the substance of the pileus descends into the gills, and that relatively the substance of the stem is more fibrous than that of the pileus. In the common mushroom the ring is very distinct surrounding the stem, a little above the middle, like a collar. In some Agarics the ring is very fugacious, or absent altogether. The form of the gills, their mode of attachment to the stem, their colour, and more especially the colour of the spores, are all very important features to be attended to in the discrimination of species, since they vary in different species. The whole substance of the Agaric is cellular. A longitudinal slice from the stem will exhibit under the microscope delicate tubular cells, the general direction of which is lengthwise, with lateral branches, the whole interlacing so intimately that it is difficult to trace any individual thread very far in its course. It will be evident that the structure is less compact as it approaches the centre of the stem, which in many species is hollow. The hymenium is the spore-bearing surface, which is exposed or naked, and spread over the gills. These plates are covered on all sides with a delicate membrane, upon which the reproductive organs are developed. If it were possible to remove this membrane in one entire piece and spread it out flat, it would cover an immense surface, as compared with the size of the pileus, for it is plaited or folded like a lady's fan over the whole of the gill-plates, or lamellae, of the fungus.[C] If the stem of a mushroom be cut off close to the gills, and the cap laid upon a sheet of paper, with the gills downwards, and left there for a few hours, when removed a number of dark radiating lines will be deposited upon the paper, each line corresponding with the interstices between one pair of gills. These lines are made up of spores which have fallen from the hymenium, and, if placed under the microscope, their character will at once be made evident. If a fragment of the hymenium be also submitted to a similar examination, it will be found that the whole surface is studded with spores. The first peculiarity which will be observed is, that these spores are almost uniformly in groups of four together. The next feature to be observed is, that each spore is borne upon a slender stalk or sterigma, and that four of these sterigmata proceed from the apex of a thicker projection, from the hymenium, called a basidium, each basidium being the supporter of four sterigmata, and each sterigma of a spore.[D] A closer examination of the hymenium will reveal the fact that the basidia are accompanied by other bodies, often larger, but without sterigmata or spores; these have been termed cystidia, and their structure and functions have been the subject of much controversy.[E] Both kinds of bodies are produced on the hymenium of most, if not all, the Agaricini.



The basidia are usually expanded upwards, so as to have more or less of a clavate form, surmounted by four slender points, or tubular processes, each supporting a spore; the contents of these cells are granular, mixed apparently with oleaginous particles, which communicate through the slender tubes of the spicules with the interior of the spores. Corda states that, although only one spore is produced at a time on each sporophore, when this falls away others are produced in succession for a limited period. As the spores approach maturity, the connection between their contents and the contents of the basidia diminishes and ultimately ceases. When the basidium which bears mature spores is still well charged with granular matter, it may be presumed that the production of a second or third series of spores is quite possible. Basidia exhausted entirely of their contents, and which have become quite hyaline, may often be observed.

The cystidia are usually larger than the basidia, varying in size and form in different species. They present the appearance of large sterile cells, attenuated upwards, sometimes into a slender neck. Corda was of opinion that these were male organs, and gave them the name of pollinaires. Hoffmann has also described[F] both these organs under the names of pollinaria and spermatia, but does not appear to recognize in them the sexual elements which those names would indicate; whilst de Seynes suggests that the cystidia are only organs returned to vegetative functions by a sort of hypertrophy of the basidia.[G] This view seems to be supported by the fact that, in the section Pluteus and some others, the cystidia are surmounted by short horns resembling sterigmata. Hoffmann has also indicated[H] the passage of cystidia into basidia. The evidence seems to be in favour of regarding the cystidia as barren conditions of basidia. There are to be found upon the hymenium of Agarics a third kind of elongated cells, called by Corda[I] basilary cells, and by Hoffmann "sterile cells," which are either equal in size or smaller than the basidia, with which also their structure agrees, excepting in the development of spicules. These are the "proper cells of the hymenium" of Leveille, and are simply the terminal cells of the gill structure—cells which, under vigorous conditions, might be developed into basidia, but which are commonly arrested in their development. As suggested by de Seynes, the hymenium seems to be reduced to great simplicity, "one sole and self-same organ is the basis of it; according as it experiences an arrest of development, as it grows and fructifies, or as it becomes hypertrophied, it gives us a paraphyse, a basidium, or a cystidium—in other terms, atrophied basidium, normal basidium and hypertrophied basidium; these are the three elements which form the hymenium."[J]

The only reproductive organs hitherto demonstrated in Agarics are the spores, or, as sometimes called, from their method of production, basidiospores.[K] These are at first colourless, but afterwards acquire the colour peculiar to the species. In size and form they are, within certain limits, exceedingly variable, although form and size are tolerably constant in the same species. At first all are globose; as they mature, the majority are ovoid or elliptic; some are fusiform, with regularly attenuated extremities. In Hygrophorus they are rather irregular, reniform, or compressed in the middle. Sometimes the external surface is rough with more or less projecting warts. Some mycologists are of opinion that the covering of the spore is double, consisting of an exospore and an endospore, the latter being very fine and delicate. In other orders the double coating of the spore has been demonstrated. When the spore is coloured, the external membrane alone appears to possess colour, the endospore being constantly hyaline. It may be added here, that in this order the spore is simple and unicellular. In Lactarius and Russula the trama, or inner substance, is vesicular. True latex vessels occur occasionally in Agaricus, though not filled with milk as in Lactarius.



POLYPOREI.—In this order the gill plates are replaced by tubes or pores, the interior of which is lined by the hymenium; indications of this structure having already been exhibited in some of the lower Agaricini. In many cases the stem is suppressed. The substance is fleshy in Boletus, but in Polyporus the greater number of species are leathery or corky, and more persistent. The basidia, spicules, and quaternate spores agree with those of Agaricini.[L] In fact there are no features of importance which relate to the hymenium in any order of Hymenomycetes (the Tremellini excepted) differing from the same organ in Agaricini, unless it be the absence of cystidia.



HYDNEI.—Instead of pores, in this order the hymenium is spread over the surface of spines, prickles, or warts.[M]

AURICULARINI.—The hymenium is more or less even, and in—

CLAVARIEI the whole fungus is club-shaped, or more or less intricately branched, with the hymenium covering the outer surface.



TREMELLINI.—In this order we have a great departure from the character of the substance, external appearance, and internal structure of the other orders in this family. Here we have a gelatinous substance, and the form is lobed, folded, convolute, often resembling the brain of some animal. The internal structure has been specially illustrated by M. Tulasne,[N] through the common species, Tremella mesenterica. This latter is of a fine golden yellow colour, and rather large size. It is uniformly composed throughout of a colourless mucilage, with no appreciable texture, in which are distributed very fine, diversely branched and anastomosing filaments. Towards the surface, the ultimate branches of this filamentous network give birth, both at their summits and laterally, to globular cells, which acquire a comparatively large size. These cells are filled with a protoplasm, to which the plant owes its orange colour. When they have attained their normal dimensions, they elongate at the summit into two, three, or four distinct, thick, obtuse tubes, into which the protoplasm gradually passes. The development of these tubes is unequal and not simultaneous, so that one will often attain its full dimensions, equal, perhaps, to three or four times the diameter of the generative cell, whilst the others are only just appearing. By degrees, as each tube attains its full size, it is attenuated into a fine point, the extremity of which swells into a spheroidal cell, which ultimately becomes a spore. Sometimes these tubes, or spicules, send out one or two lateral branches, each terminated by a spore. These spores (about .006 to .008 mm. diameter) are smooth, and deposit themselves, like a fine white dust, on the surface of the Tremella and on its matrix. M. Leveille[O] was of opinion that the basidia of the Tremellini were monosporous, whilst M. Tulasne has demonstrated that they are habitually tetrasporous, as in other of the Hymenomycetes. Although agreeing in this, they differ in other features, especially in the globose form of the basidia, mode of production of the spicules, and, finally, the division of the basidia into two, three, or four cells by septa which cut each other in their axis. This division precedes the growth of the spicules. It is not rare to see these cells, formed at the expense of an unilocular basidium, become partly isolated from each other; in certain cases they seem to have separated very early, they then become larger than usual, and are grouped on the same filament so as to represent a kind of buds. This phenomenon usually takes place below the level of the fertile cells, at a certain depth in the mucous tissue of the Tremella.

Besides the reproductive system here described, Tulasne also made known the existence of a series of filaments which produce spermatia. These filaments are often scattered and confused with those which produce the basidia, and not distinguishable from them in size or any other apparent characteristic, except the manner in which their extremities are branched in order to produce the spermatia. At other times the spermatia-bearing surface covers exclusively certain portions of the fungus, especially the inferior lobes, imparting thereto a very bright orange colour, which is communicated by the layer of spermatia, unmixed with spores. These spots retain their bright colour, while the remainder of the plant becomes pale, or covered with a white dust. The spermatia are very small, spherical, and smooth, scarcely equalling .002 mm. They are sessile, sometimes solitary, sometimes three or four together, on the slightly swollen extremities of certain filaments of the weft of the fungus.[P] Tulasne found it impossible to make these corpuscles germinate, and in all essential particulars they agreed with the spermatia found in ascomycetous fungi.

In the genus Dacrymyces, the same observer found the structure to have great affinity with that of Tremella. The spores in the species examined were of a different form, being oblong, very obtuse, slightly curved (.013 - .019 x .004 - .006 mm.), at first unilocular, but afterwards triseptate. The basidia are cylindrical or clavate, filled with coloured granular matter; each of these bifurcates at the summit, and gradually elongates into two very open branches, which are attenuated above, and ultimately each is crowned by a spore. There are to be found also in the species of this genus globose bodies, designated "sporidioles" by M. Leveille, which Tulasne took considerable care to trace to their source. He thus accounts for them:—Each of the cells of the spore emits exteriorly one or several of these corpuscles, supported on very short and very slender pedicels, which remain after the corpuscles are detached from them, new corpuscles succeeding the first as long as there remains any plastic matter within the spore. The pedicels are not all on the same plane; they are often implanted all on the same, and oftenest on the convex side of the reproductive body. These corpuscles, though placed under the most favourable conditions, never gave the least sign of vegetation, and Tulasne concludes that they are spermatia, analogous to those produced in Tremella. The spores which produce spermatia are not at all apt to germinate, whilst those which did not produce spermatia germinated freely. Hence it would appear that, although all spores seem to be perfectly identical, they have not all the same function. The same observer detected also amongst specimens of the Dacrymyces some of a darker and reddish tint, always bare of spores or spermatia on the surface, and these presented a somewhat different structure. Where the tissue had turned red it was sterile, the constituent filaments, ordinarily colourless, and almost empty of solid matter, were filled with a highly-coloured protoplasm; they were of less tenuity, more irregularly thick, and instead of only rarely presenting partitions, and remaining continuous, as in other parts of the plant, were parcelled out into an infinity of straight or curved pieces, angular and of irregular form, especially towards the surface of the fungus, where they compose a sort of pulp, varying in cohesion according to the dry or moist condition of the atmosphere. All parts of these reddish individuals seemed more or less infected with this disintegration, the basidia divided by transverse diaphragms into several cylindrical or oblong pieces, which finally become free. Transitional conditions were also observed in mixed individuals. This sterile condition is called by Tulasne "gemmiparous," and he believes that it has ere now given origin to one or more spurious species, and misled mycologists as to the real structure of perfect and fruitful Dacrymyces.

PHALLOIDEI.—In this order the hymenium is at first enclosed within a sort of peridium or universal volva, maintaining a somewhat globose or egg-shape. This envelope consists of an outer and inner coat of somewhat similar texture, and an intermediate gelatinous layer, often of considerable thickness. When a section is made of the fungus, whilst still enclosed in the volva, the hymenium is found to present numerous cavities, in which basidia are developed, each surmounted by spicules (four to six) bearing oval or oblong spores.[Q] It is very difficult to observe the structure of the hymenium in this order, on account of its deliquescent nature. As the hymenium approaches maturity, the volva is ruptured, and the plant rapidly enlarges. In Phallus, a long erect cellular stem bears the cap, over which the hymenium is spread, and this expands enormously after escaping the restraint of the volva. Soon after exposure, the hymenium deliquesces into a dark mucilage, coloured by the minute spores, which drips from the pileus, often diffusing a most loathsome odour for a considerable distance. In Clathrus, the receptacle forms a kind of network. In Aseroee, the pileus is beautifully stellate. In many the attractive forms would be considered objects of beauty, were it not for their deliquescence, and often foetid odour.[R]



PODAXINEI.—This is a small but very curious group of fungi, in which the peridium resembles a volva, which is more or less confluent with the surface of the pileus. They assume hymenomycetal forms, some of them looking like Agarics, Boleti, or species of Hydnum, with deformed gills, pores, or spines; in Montagnites, in fact, the gill structure is very distinct. The spores are borne in definite clusters on short pedicels in such of the genera as have been examined.[S]

HYPOGAEI.—These are subterranean puff-balls, in which sometimes a distinct peridium is present; but in most cases it consists entirely of an external series of cells, continuous with the internal structure, and cannot be correctly estimated as a peridium. The hymenium is sinuous and convolute, bearing basidia with sterigmata and spores in the cavities. Sometimes the cavities are traversed by threads, as in the Myxogastres. The spores are in many instances beautifully echinulate, sometimes globose, at others elongated, and produced in such numbers as to lead to the belief that their development is successive on the spicules. When fully matured, the peridia are filled with a dusty mass of spores, so that it is scarcely possible in this condition to gain any notion of the structure. This is, indeed, the case with nearly all Gasteromycetes. The hypogaeous fungi are curiously connected with Phalloidei by the genus Hysterangium.



TRICHOGASTRES.[T]—In their early stages the species contained in this group are not gelatinous, as in the Myxogastres, but are rather fleshy and firm. Very little has been added to our knowledge of structure in this group since 1839 and 1842, when one of us wrote to the following effect:—If a young plant of Lycoperdon coelatum or L. gemmatum be cut through and examined with a common pocket lens, it will be found to consist of a fleshy mass, perforated in every direction with minute elongated, reticulated, anastomosing, labyrinthiform cavities. The resemblance of these to the tubes of Boleti in an early stage of growth, first led me to suspect that there must be some very close connection between them. If a very thin slice now be taken, while the mass is yet firm, and before there is the slightest indication of a change of colour, the outer stratum of the walls of these cavities is found to consist of pellucid obtuse cells, placed parallel to each other like the pile of velvet, exactly as in the young hymenium of an Agaric or Boletus. Occasionally one or two filaments cross from one wall to another, and once I have seen these anastomose. At a more advanced stage of growth, four little spicules are developed at the tips of the sporophores, all of which, as far as I have been able to observe, are fertile and of equal height, and on each of these spicules a globose spore is seated. It is clear that we have here a structure identical with that of the true Hymenomycetes, a circumstance which accords well with the fleshy habit and mode of growth. There is some difficulty in ascertaining the exact structure of the species just noticed, as the fruit-bearing cells, or sporophores, are very small, and when the spicules are developed the substance becomes so flaccid that it is difficult to cut a proper slice, even with the sharpest lancet. I have, however, satisfied myself as to the true structure by repeated observations. But should any difficulty arise in verifying it in the species in question, there will be none in doing so in Lycoperdon giganteum. In this species the fructifying mass consists of the same sinuous cavities, which are, however, smaller, so that the substance is more compact, and I have not seen them traversed by any filaments. In an early stage of growth, the surface of the hymenium, that is of the walls of the cavities, consists of short threads composed of two or three articulations, which are slightly constricted at the joints, from which, especially from the last, spring short branchlets, often consisting of a single cell. Sometimes two or more branchlets spring from the same point. Occasionally the threads are constricted without any dissepiments, the terminal articulations are obtuse, and soon swell very much, so as greatly to exceed in diameter those on which they are seated. When arrived at their full growth, they are somewhat obovate, and produce four spicules, which at length are surmounted each with a globose spore. When the spores are fully developed, the sporophores wither, and if a solution of iodine be applied, which changes the spores to a rich brown, they will be seen still adhering by their spicules to the faded sporophores. The spores soon become free, but the spicule often still adheres to them; but they are not attached to the intermingled filaments. In Bovista plumbea, the spores have very long peduncles.[U] As in the Hymenomycetes, the prevailing type of reproductive organs consisted of quaternary spores borne on spicules; so in Gasteromycetes, the prevailing type, in so far as it is yet known, is very similar, in some cases nearly identical, consisting of a definite number of minute spores borne on spicules seated on basidia. In a very large number of genera, the minute structure and development of the fructification (beyond the mature spores) is almost unknown, but from analogy it may be concluded that a method prevails in a large group like the Myxogastres which does not differ in essential particulars from that which is known to exist in other groups. The difficulties in the way of studying the development of the spores in this are far greater than in the previous order.



MYXOGASTRES.—At one time that celebrated mycologist, Professor De Bary, seemed disposed to exclude this group from the vegetable kingdom altogether, and relegate them to a companionship with amoeboid forms. But in more recent works he seems to have reconsidered, and almost, if not entirely, abandoned, that disposition. These fungi, mostly minute, are characterized in their early stages by their gelatinous nature. The substance of which they are then composed bears considerable resemblance to sarcode, and, did they never change from this, there might be some excuse for doubting as to their vegetable nature; but as the species proceed towards maturity they lose their mucilaginous texture, and become a mass of spores, intermixed with threads, surrounded by a cellular peridium. Take, for instance, the genus Trichia, and we have in the matured specimens a somewhat globose peridium, not larger than a mustard seed, and sometimes nearly of the same colour; this ultimately ruptures and exposes a mass of minute yellow spherical spores, intermixed with threads of the same colour.[V] These threads, when highly magnified, exhibit in themselves a spiral arrangement, which has been the basis of some controversy, and in some species these threads are externally spinulose. The chief controversy on these threads has been whether the spiral markings are external or internal, whether caused by twisting of the thread or by the presence of an external or internal fibre. The spiral appearance has never been called in question, only the structure from whence it arises, and this, like the striae of diatoms, is very much an open question. Mr. Currey held that the spiral appearance may be accounted for by supposing the existence of an accurate elevation in the wall of the cell, following a spiral direction from one end of the thread to the other. This supposition would, he thinks, accord well with the optical appearances, and it would account exactly for the undulations of outline to which he alludes. He states that he had in his possession a thread of Trichia chrysosperma, in which the spiral appearance was so manifestly caused by an elevation of this nature, in which it is so clear that no internal spiral fibre exists, that he did not think there could be a doubt in the mind of any person carefully examining it with a power of 500 diameters that the cause of the spiral appearance was not a spiral fibre. In Arcyria, threads of a different kind are present; they mostly branch and anastomose, and are externally furnished with prominent warts or spines, which Mr. Currey[W] holds are also arranged in a spiral manner around the threads. In other Myxogastres, threads are also present without any appreciable spiral markings or spines. In the mature condition of these fungi, they so clearly resemble, and have such close affinities with, the Trichogastres that one is led almost to doubt whether it was not on hasty grounds, without due examination or consideration, that proposals were made to remove them from the society of their kindred.



Very little is known of the development of the spores in this group; in the early stages the whole substance is so pulpy, and in the latter so dusty, whilst the transition from one to the other is so rapid, that the relation between the spores and threads, and their mode of attachment, has never been definitely made out. It has been supposed that the spinulose projections from the capillitium in some species are the remains of pedicels from which, the spores have fallen, but there is no evidence beyond this supposition in its favour, whilst on the other hand, in Stemonitis, for instance, there is a profuse interlacing capillitium, and no spines have been detected. In order to strengthen the supposition, spines should be more commonly present. The threads, or capillitium, form a beautiful reticulated network in Stemonitis, Cribraria, Diachaea, Dictydium, &c. In Spumaria, Reticularia, Lycogala, &c., they are almost obsolete.[X] In no group is the examination of the development of structure more difficult, for the reasons already alleged, than in the Myxogastres.



NIDULARIACEI.—This small group departs in some important particulars from the general type of structure present in the rest of the Gasteromycetes.[Y] The plants here included may be described under three parts, the mycelium, the peridium, and the sporangia. The mycelium is often plentiful, stout, rigid, interlacing, and coloured, running over the surface of the soil, or amongst the vegetable debris on which the fungi establish themselves. The peridia are seated upon this mycelium, and in most instances are at length open above, taking the form of cups, or beakers. These organs consist of three strata of tissue varying in structure, the external being fibrous, and sometimes hairy, the interior cellular and delicate, the intermediate thick and at length tough, coriaceous, and resistant. When first formed, the peridia are spherical, they then elongate and expand, the mouth being for some time closed by a veil, or diaphragm, which ultimately disappears. Within the cups lentil-shaped bodies are attached to the base and sides by elastic cords. These are the sporangia. Each of these has a complicated structure; externally there is a filamentous tunic, composed of interlaced fibres, sometimes called the peridiole; beneath this is the cortex, of compact homogenous structure, then follows a cellular thicker stratum, bearing, towards the centre of the sporangia, delicate branched threads, or sporophores, on which, at their extremities, the ovate spores are generated, sometimes in pairs, but normally, it would seem that they are quaternary on spicules, the threads being true basidia. The whole structure is exceedingly interesting and peculiar, and may be studied in detail in Tulasne's memoir on this group.

SPHAERONEMEI.—In this very large and, within certain limits, variable order, there is but little of interest as regards structure, which is not better illustrated elsewhere; as, for instance, some sort of perithecium is always present, but this can be better studied in the Sphaeriacei. The spores are mostly very minute, borne on delicate sporophores, which originate from the inner surface of the perithecia, but the majority of so-called species are undoubtedly conditions of sphaeriaceous fungi, either spermatogonia or pycnidia, and are of much more interest when studied in connection with the higher forms to which they belong.[Z] Probably the number of complete and autonomous species are very few.



MELANCONIEI.—Here, again, are associated together a great number of what formerly were considered good species of fungi, but which are now known to be but conditions of other forms. One great point of distinction between these and the preceding is the absence of any true perithecium, the spores being produced in a kind of spurious receptacle, or from a sort of stroma. The spores are, as a rule, larger and much more attractive than in Sphaeronemei, and, in some instances, are either very fine, or very curious. Under this head we may mention the multiseptate spores of Coryneum; the tri-radiate spores of Asterosporium; the curious crested spores of Pestalozzia; the doubly crested spores of Dilophospora; and the scarcely less singular gelatinous coated spores of Cheirospora. In all cases the fructification is abundant, and the spores frequently ooze out in tendrils, or form a black mass above the spurious receptacle from which they issue.[a]



TORULACEI.—In this order there seems at first to be a considerable resemblance to the Dematiei, except that the threads are almost obsolete, and the plant is reduced to chains of spores, without trace of perithecium, investing cuticle, or definite stroma. Sometimes the spores are simple, in other cases septate, and in Sporochisma are at first produced in an investing cell. In most cases simple threads at length become septate, and are ultimately differentiated into spores, which separate at the joints when fully mature.



CAEOMACEI.—Of far greater interest are the Coniomycetous parasites on living plants. The present order includes those in which the spore[b] is reduced to a single cell; and here we may observe that, although many of them are now proved to be imperfect in themselves, and only forms or conditions of other fungals, we shall write of them here without regard to their duality. These originate, for the most part, within the tissues of living plants, and are developed outwards in pustules, which burst through the cuticle. The mycelium penetrates the intercellular passages, and may sometimes be found in parts of the plants where the fungus does not develop itself. There is no proper excipulum or peridium, and the spores spring direct from a more compacted portion of the mycelium, or from a cushion-like stroma of small cells. In Lecythea, the sub-globose spores are at first generated at the tips of short pedicels, from which they are ultimately separated; surrounding these spores arise a series of barren cells, or cysts, which are considerably larger the true spores, and colourless, while the spores are of some shade of yellow or orange.[c] In Trichobasis, the spores are of a similar character, sub-globose, and at first pedicellate; but there are no surrounding cysts, and the colour is more usually brown, although sometimes yellow. In Uredo, the spores are at first generated singly, within a mother cell; they are globose, and either yellow or brown, without any pedicel. In Coleosporium, there are two kinds of spores, those of a pulverulent nature, globose, which are sometimes produced alone at the commencement of the season, and others which originate as an elongated cell; this becomes septate, and ultimately separates at the joints. During the greater part of the year, both kinds of spores are to be found in the same pustule. In Melampsora, the winter spores are elongated and wedge-shaped, compacted together closely, and are only matured during winter on dead leaves; the summer spores are pulverulent and globose, being, in fact, what were until recently regarded as species of Lecythea. In Cystopus, the spores are sub-globose, or somewhat angular, generated in a moniliform manner, and afterwards separating at the joints. The upper spore is always the oldest, continuous production of spores going on for some time at the base of the chain. Under favourable conditions of moisture, each of these spores, or conidia, as De Bary terms them, is capable of producing within itself a number of zoospores;[d] these ultimately burst the vesicle, move about by the aid of vibratile cilia, and at last settle down to germinate. Besides these, other reproductive bodies are generated upon the mycelium, within the tissues of the plant, in the form of globose oogonia, or resting spores, which, when mature, also enclose great numbers of zoospores. Similar oogonia are produced amongst the Mucedines in the genus Peronospora, to which De Bary considers Cystopus to be closely allied. At all events, this is a peculiarity of structure and development not as yet met with in any other of the Caeomacei. In Uromyces is the nearest approach to the Pucciniaei; in fact, it is Puccinia reduced to a single cell. The form of spore is usually more angular and irregular than in Trichobasis, and the pedicel is permanent. It may be remarked here, that of the foregoing genera, many of the species are not autonomous that have hitherto been included amongst them. This is especially true of Lecythea, Trichobasis, and, as it now appears, of Uromyces.[e]



PUCCINIAEI.—This group differs from the foregoing chiefly in having septate spores. The pustules, or sori, break through the cuticle in a similar manner, and here also no true peridium is present. In Xenodochus, the highest development of joints is reached, each spore being composed of an indefinite number, from ten to twenty cells. With it is associated an unicellular yellow Uredine, of which it is a condition. Probably, in every species of the Pucciniaei, it may hereafter be proved, as it is now suspected, that an unicellular Uredine precedes or is associated with it, forming a condition, or secondary form of fruit of that species. Many instances of that kind have already been traced by De Bary,[f] Tulasne, and others, and some have been a little too rashly surmised by their followers. In Phragmidium, the pedicel is much more elongated than in Xenodochus, and the spore is shorter, with fewer and a more definite number of cells for each species; Mr. Currey is of opinion that each cell of the spore in Phragmidium has an inner globose cell, which he caused to escape by rupture of the outer cell wall as a sphaeroid nucleus,[g] leading to the inference that each cell has its own individual power of germination and reproduction. In Triphragmium, there are three cells for each spore, two being placed side by side, and one superimposed. In one species, however, Triphragmium deglubens (North American), the cells are arranged as in Phragmidium, so that this represents really a tricellular Phragmidium, linking the present with the latter genus. In Puccinia the number of species is by far the most numerous; in this genus the spores are uniseptate, and, as in all the Pucciniaei, the peduncles are permanent. There is great variability in the compactness of the spores in the sori, or pulvinules. In some species, the sori are so pulverulent that the spores are as readily dispersed as in the Uredines, in others they are so compact as to be separated from each other with great difficulty. As might be anticipated, this has considerable effect on the contour of the spores, which in pulverulent species are shorter, broader, and more ovate than in the compact species. If a section of one of the more compact sori be made, it will be seen that the majority of the spores are side by side, nearly at the same level, their apices forming the external surface of the sori, but it will not be unusual to observe smaller and younger spores pushing up from the hymenial cells, between the peduncles of the elder spores, leading to the inference that there is a succession of spores produced in the same pulvinule. In Podisoma, a rather anomalous genus, the septate spores are immersed in a gelatinous stratum, and some authors have imagined that they have an affinity with the Tremellini, but this affinity is more apparent than real. The phenomena of germination, and their relations to Roestelia, if substantiated, establish their claim to a position amongst the Pucciniaei.[h] It seems to us that Gymnosporangium does not differ generically from Podisoma. In a recently-characterized species, Podisoma Ellisii, the spores are bi-triseptate. This is, moreover, peculiar from the great deficiency in the gelatinous element. In another North American species, called Gymnosporangium biseptatum, Ellis, which is distinctly gelatinous, there are similar biseptate spores, but they are considerably broader and more obtuse. In other described species they are uniseptate.



USTILAGINEI.—These fungi are now usually treated as distinct from the Caeomacei, to which they are closely related.[i] They are also parasitic on growing plants, but the spores are usually black or sooty, and never yellow or orange; on an average much smaller than in the Caeomacei. In Tilletia, the spores are spherical and reticulated, mixed with delicate threads, from whence they spring. In the best known species, Tilletia caries, they constitute the "bunt" of wheat. The peculiarities of germination will be alluded to hereafter. In Ustilago, the minute sooty spores are developed either on delicate threads or in compacted cells, arising first from a sort of semi-gelatinous, grumous stroma. It is very difficult to detect any threads associated with the spores. The species attack the flowers and anthers of composite and polygonaceous plants, the leaves, culms, and germen of grasses, &c., and are popularly known as "smuts." In Urocystis and Thecaphora, the spores are united together into sub-globose bodies, forming a kind of compound spore. In some species of Urocystis, the union which subsists between them is comparatively slight. In Thecaphora, on the contrary, the complex spore, or agglomeration of spores, is compact, being at first apparently enclosed in a delicate cyst. In Tuburcinia, the minute cells are compacted into a hollow sphere, having lacunae communicating with the interior, and often exhibiting the remains of a pedicel.



AECIDIACEI.—This group differs from the foregoing three groups prominently in the presence of a cellular peridium, which encloses the spores; hence some mycologists have not hesitated to propose their association with the Gasteromycetes, although every other feature in their structure seems to indicate a close affinity with the Caeomacei. The pretty cups in the genus AEcidium are sometimes scattered and sometimes collected in clusters, either with spermogonia in the centre or on the opposite surface. The cups are usually white, composed of regularly arranged bordered cells at length bursting at the apex, with the margins turned back and split into radiating teeth. The spores are commonly of a bright orange or golden yellow, sometimes white or brownish, and are produced in chains, or moniliform strings, slightly attached to each other,[j] and breaking off at the summit at the same time that they continue to be produced at the base, so that for some time there is a successive production of spores. The spermogonia are not always readily detected, as they are much smaller than the peridia, and sometimes precede them. The spermatia are expelled from the lacerated and fringed apices, and are very minute and colourless. In Roestelia the peridia are large, growing in company, and splitting longitudinally in many cases, or by a lacerated mouth. In most instances, the spores are brownish, but in a splendid species from North America (Roestelia aurantiaca, Peck), recently characterized, they are of a bright orange. If Oersted is correct in his observations, which await confirmation, these species are all related to species of Podisoma as a secondary form of fruit.[k] In the Roestelia of the pear-tree, as well as in that of the mountain ash, the spermogonia will be found either in separate tufts on discoloured spots, or associated with the Roestelia, In Peridermium there is very little structural difference from Roestelia, and the species are all found on coniferous trees. In Endophyllum, the peridia are immersed in the succulent substance of the matrix; whilst in Graphiola, there is a tougher and withal double peridium, the inner of which forms a tuft of erect threads resembling a small brush.[l]



HYPHOMYCETES.—The predominant feature in the structure of this order has already been intimated to consist in the development of the vegetative system under the form of simple or branched threads, on which the fruit is generated. The common name of mould is applied to them perhaps more generally than to other groups, although the term is too vague, and has been too vaguely applied to be of much service in giving an idea of the characteristics of this order. Leaving the smaller groups, and confining ourselves to the Dematiei and the Mucedines, we shall obtain some notion of the prevalent structure. In the former the threads are more or less carbonized, in the latter nearly colourless. One of the largest genera in Dematiei is Helminthosporium. It appears on decaying herbaceous plants, and on old wood, forming effused black velvety patches. The mycelium, of coloured jointed threads, overlays and penetrates the matrix; from this arise erect, rigid, and usually jointed threads, of a dark brown, nearly black colour at the base, but paler towards the apex. In most cases these threads have an externally cortical layer, which imparts rigidity; usually from the apex, but sometimes laterally, the spores are produced. Although sometimes colourless, these are most commonly of some shade of brown, more or less elongated, and divided transversely by few or many septa. In Helminthosporium Smithii, the spores much exceed the dimensions of the threads;[m] in other species they are smaller. In Dendryphium, the threads and spores are very similar, except that the threads are branched at their apex, and the spores are often produced one at the end of another in a short chain.[n] In Septosporium again, the threads and spores are similar, but the spores are pedicellate, and attached at or near the base; whilst in Acrothecium, with similar threads and spores, the latter are clustered together at the apex of the threads. In Triposporium, the threads are similar, but the spores are tri-radiate; and in Helicoma, the spores are twisted spirally. Thus, we might pass through all the genera to illustrate this chief feature of coloured, septate, rather rigid, and mostly erect threads, bearing at some point spores, which in most instances are elongated, coloured, and septate.