173 The Fungi of Wiltshire. 



by bodies usually inclosed in asci, called sporidia, as well as by 

 green bodies, called gonidia, which occur in their frond or thallus. 

 Fungi derive their nourishment through their mycelium from the 

 substance on which they grow, and are chiefly propagated by 

 bodies, called, according to the mode in which they are developed, 

 sporidia or spores. They may be defined as flowerless plants, 

 formed of cells or threads, or both combined, growing chiefly on 

 decaying organic substances, or on earth, a few only occurring on 

 living animal, or vegetable, tissues, variously coloured, and never 

 accompanied by reproductive green bodies, like Lichens. Their 

 fructification consists either of cells attached externally to threads 

 which either arise immediately from their mycelium, or from an 

 especial fructificative tissue, and which are then called spores ; or 

 of similar bodies produced in little sacs or tubes, and then called 

 sporidia. Spiral filaments exist in a few genera. Fungi are said 

 to absorb oxygen, and exhale carbonic acid, thus performing rather 

 the functions of an animal, than of a vegetable ; in consonance 

 with which is the fact of their never assuming a true vegetable 

 green colour, but where green at all, they are of a metallic tint. 

 They may be considered as the scavengers of the vegetable king- 

 dom ; no sooner does a plant die, than it is occupied by a variety 

 of species, whose mycelium penetrates it in every direction, and 

 lends its aid to its speedy disintegration. They do not however 

 confine their operation to dead herbaceous, or soft-stemmed plants, 

 but often attack hard woody trunks, and then produce a speedy 

 decay in timber, which might have resisted the mere action of the 

 weather for many years. The Dry Rot, Merulius lacrymans, affords 

 us a good illustration. When perfect, this is a very handsome 

 species, several others however attack timber. Some take possession 

 of living vegetable tissues, chiefly perhaps such as are suffering from 

 atmospheric, or other causes. We may here instance the potatoe 

 disease, produced by Peronospora infestans, and the vine disease, 

 bv Oidium Tuckeri. Those great enemies to the farmer, Rust, 

 Smut, and Bunt, are caused by Uredo rubigo, Uredo segetum, 

 and Uredo caries, which attack the cereals in a growing state. 

 Nor are aijimal tissues exempted from the mischief produced by 



