Fungi: Their Nature and Uses

pheyn - M. C. (Mordecai Cubitt) Cooke

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Publié par	pheyn
Publié le	01 décembre 2010
Nombre de lectures	128
Langue	English

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. 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.” Schwendener, “Untersuchungen über den Flechtenthallus.” Crombie (J. M.) “On the Lichen-Gonidia Question,” in “Popular Science Review” for July, 1874. Bornet, (E.), “Recherches sur les Gonidies des Lichens,” in “Ann. des Sci. Nat.” 1873, 5 sér. vol. xvii. Nylander, “On the Algo-Lichen Hypothesis,” &c., in “Grevillea,” vol. ii. (1874), No. 22, p. 146. In Regensburg “Flora,” 1870, p. 92. Rev. J. M. Crombie, in “Popular Science Review,” July, 1874. Berkeley’s “Introduction to Cryptogamic Botany,” p. 373, fig. 78a. [Pg 16] [Pg 8] [Pg 9] [Pg 10] [Pg 11] [Pg 12] [Pg 13] [Pg 14] [Pg 15] [J] [K] [L] [M] [N] [O] [P] Berkeley’s “Introduction,” p. 341, fig. 76. “Annals and Magazine of Natural History,” April, 1849. In “Gardener’s Chronicle” for 1873, p. 1341. “Grevillea,” vol ii. p. 147, in note. 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. FIG. 1.—Agaric in Process of Growth. 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

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