950 XIII. FUNGI. 



or are parasites on vast numbers of Phsenogamous plants, and even on other Fungi; 

 some are developed in living animal tissues, and are the reputed causes of various 

 diseases. They are very rarely found on stones, or in water. In no particular can 

 they be compared with Phsenogams, having no organs comparable with loaves and 

 flowers. Among Acotyledons, they approach Algce in their vegetation, and Lichens 

 in their fructification, but they have no fronds ; and no known Fungus reeembles a 

 unicellular Alga. 



In- a Mushroom or Toadstool the following organs are distinguished : — the myce- 

 lium, the volva, the stipe {or pedicel), the receptacle or pileus, the coneeptacle, the basidia, 

 the thecoB, and the spores. 



The mycelium, fulfils at once the functions of root and stem ; this, of which the 

 Mushroom spawn is an instance, is the result of the vegetation of the spores. It is 

 composed of cells, originally free, variable in colour, more or less elongated, and is 

 sometimes so scanty as to escape observation. It appears, when completely developed, 

 under four different forms : 1. The filamentous or nematoid is composed of elongated 

 branched cells, isolated, or collected in threads. 2. The membranous or hymenoid is 

 composed of cells united into a membrane of diverse texture. 3. The pulpy or 

 malacoid presents a soft and pulpy, branched or grumous mass ; in this case the 

 granules which compose it present a remarkable analogy with the protozoid animal- 

 cules called AmoebcB, and with animal sarcode; this form of mycelium, placed in 

 water, vegetates, but does not fructify. 4. The tubercular or scleroid consists of 

 globose or flattened regular or irregular tubercles, of a firm texture, homogeneous 

 structure, and composed of extremely minute cells. This scleroid form, which plays 

 a very important part in the vegetation of Fungi, is only a transitory one ; it always 

 proceeds from the filamentous state, and may be compared with the tubers of the 

 Potato, and not with a true subterranean stem ; its life is truly latent, and only 

 preserved by the hygrometric nature of its tissue. In a favourable season the 

 scleroid mycelium becomes saturated with moisture, and either develops a perfect 

 Fungus itself, or a nematoid'mycelium, which again develops perfect individuals. Its 

 function is analogous to the albumen of an amylaceous seed, or of a tuber, the 

 substance of which is exhausted as the plant it nourishes grows, and leaves only 

 a cortical membrane. It is thus that the Agaricus tuberosus is developed from 

 Sclerotium cornutum., A. racemosus from 8. lacunosum, Glavaria phacorrhiza from 

 some other Sclerotium; it is the same with certain Pezisoe (P. tuberosa, Candolleana, 

 &c.), and with Botrytis cinerea, which grows indifferently on various corms of 

 Sclerotia (S. durum, compactum, medullosum, &c.). The mycelium is lemarJrable for 

 its power of retaining vitality long after it has been collected, starting into life as 

 soon as placed under favourable conditions, reproducing its filaments, and extendino- 

 indefinitely and consuming the organic substances it meets with, until exposed 

 to the influence of light, which enables it to produce its organs of fructification. 



The volva is the more or less firm and membranous envelope or pouch, which 

 contains the young Fungus, and which the latter bursts through as it develops 

 (Amanita, &G.) . The pedicel ov stipes is the stem-like portion which supports the 

 rfceptacle ; it is often surrounded by a ring [annulus), or a cortina, membranous or 



