F. generally grow in damp situations, hut there are many which occur chiefly on dry soils or on dry substances; and some appear in their greatest perfection in the finest summer weather, although many are most abundant in the colder and moister seasons of the year. It has been commonly asserted that they abound more in the colder parts of the world than within the tropics, but it is not improbable that this opinion has its origin merely in imperfect observation of tropical species. The extreme rapidity of their growth, the briefness of their whole existence, the readiness with which they pass into decomposition, and the difficulty of preserving most of them in a form fit for examination, have been great obstacles to their scientific study. It is known, however, that sonic species are of very wide geographic distribution, whilst others are compara tively very limited. Some species grow in earth, others in various kinds of putrescent or fermenting animal or vegetable matter, many in decaying parts of trees or on dead wood, others on diseased animal and vegetable tissues, etc. It appears to be the office of many of them to hasten the decomposition of animal, and more particularly of vege table substances. Some of the minute kinds appear to be the cause of disease iu the higher kinds of plants which they attack, and are formidable to the farmer and the gardener. Some are in like manner destructive to animal life, as in the case of the muscardine (q.v.) or silk-worm rot, and certain species of spharia which grow from living caterpillars. See ENTOPHYTES.
Some F. are remarkably phosphorescent. Thus mycelium of some kind produces a very beautiful luminosity in some German coal-mines; and a species of agaric (agaricus gardnen), growing on palms in Brazil, shines brightly in the night. 2garicus olearius, a native of the s. of Europe, is also luminous.
The chemical examination of F. yields in large quantity a substance called fungine, which, however, is now regarded as consisting of cellulose and fatty matter, several other nitrogenous substances, an acid called fungic acid, a kind of sugar, etc. The poisonous properties of some:are ascribed to an alkaloid called amanitine. Others appear to owe their poisonous character to an acrid volatile substance. Many of the smaller F. are important because of the injury which they cause to crops, timber, etc. A few species are used in medicine, of which the only one really important is ergot of rye. One or two are used as tinder (see AmAnon), moxa (q.v.), etc. The smoke pro duced by burning the dust (spores) of ripened puff-balls has antusthetic properties, and is used for stupefying bees. Polyporus squamosus cut into slices makes the best of razor strops. But the chief economical use of F. is for food, and in the manufacture 'of the sauce called ketchup (q.v.).
Edible fungi of the hymenomycetes, gasteromycetes, and ascomy cetes are edible; and some of them are much esteemed as delicacies, whilst in many countries they constitute an important part of the food of the people. In Britain, very few are used, many of those species which are most esteemed on the continent of Europe being utterly disregarded, and indeed classed in popular estimation with toad-stools as poisonous. The truth appears to be, not that the greater number are poisonous, and only a few edible, but that the noxious species are comparatively few, the principal danger arising from the similarity of some of the poisonous and some of the edible *gams, and from the liability of some of the edible species to acquire poisonous prop erties in particular situations and circumstances. This is notably the case with the common mushroom (agaricus campestris), which is far more generally used in Britain than any other edible fungus, but of which some varieties are unsafe, apparently in consequence of the circumstances of their growth. From the markets of Rome, and other cities of Italy, where numerous species of fungi are extensively sold, this species is rigorously excluded. So important an article of food are F. in Italy, that in the market of Rome alone they are supposed to be sold to the value of about £4,000 a year. For weeks, both in spring and in autumn, F. form the principal and, almost the sole food of multitudes of the poor in Italy, Germany, and France; and besides those which are eaten fresh, great quantities are used dried or preserved in oil, vinegar, or brine. The soaking of F. in vinegar or brine takes away the acrid qualities of some which are dangerous when fresh, and renders them perfectly safe. So valuable are F. esteemed, that some species are frequently cultivated. The cultivation of the common mushroom (q:v.) is familiar to us in Britain, but other species of agaricus, boletus, etc., are plenti fully raised in some parts of the continent of Europe, by watering the ground in places appropriate for them with water. in which mature plants abounding in spores have been bruised; others are obtained by merely placing in favorable circumstances substances in which their spores are already contained. Thus, a species of polyporus, much esteemed, is procured in Italpby moistening the porous stone (Ital., Pietra funghaia) over which a little earth has been scattered; another species of polyporus, by slightly charring and then watering blocks of the wood of the common hazel; a species of agaricus, by cutting off and then watering the heads of black poplar trees; and another agaricus, by placing the grounds of coffee in circumstances favorable for its growth.