In the preceding family (Hymenomycetes) the fruit-bearing surface has free access to the air, but in the group of the GASTEROMYCETES, which consists of five or six sub-orders, it has neither access to air or light till the fruit is ripe, for the fructification is enclosed in a rind of one or two coats, and springs without a stem from a gelatinous thready, or cellular mycelium. The most important group, Trichogastres, includes the puff-balls, which grow on the ground. Of these the Lycoperdon, found everywhere on pasture grounds and meadows, is a familiar instance. When young it has a milk-white coat filled with closely packed cells, some of which bear naked spores set upon spicules. When mature, the whole of the interior vanishes, leaving nothing but a mass of threads and fruit; the coat becomes brown, bursts open at the top, and gives vent to a cloud of microscopic spores like the finest dust. In general the ball is sessile, or it has merely the rudiment of a stem. The Lycoperdon giganteum, an exceedingly large species, is a native of a warm climate. The tops of some of the branched threads of its hymenium swell into pear-shaped cells surmounted by short spicules ending in spores; when young it is edible, when dry it is used for tinder and as a styptic, and when ignited its fumes possess a property similar to that of chloroform. The Batarrea forms a contrast to the common puff-balls, being mounted on a stem sometimes a foot and a half high. It has several coats enclosing a thick gelatinous substance in which the threads carrying the spores are distinctly spiral and closely twisted. The sub-order Hypogæi is subterranean, as the name implies. The exterior coat of these fungi is inseparable from the internal matter, which is for the most part fleshy. In some species it is dry, in others it abounds in milky juice; but in all the fruit is formed in hollows excavated in the interior mass. In some species these cavities are traversed by threads, and in many species the spores accumulate in such multitudes within the cavities, as to make it certain that the spicules, on which the spores are borne, produce successive crops. They are set free by the rupture of the rind. A species of the genus Melanogaster, abundant in the south of England, is edible and sold as the red truffle of Bath; but it is far inferior to the real truffle.