The only reproductive organs hitherto demonstrated in Agarics are the spores, or, as sometimes called, from their method of production, _basidiospores_.[K] These are at first colourless, but afterwards acquire the colour peculiar to the species. In size and form they are, within certain limits, exceedingly variable, although form and size are tolerably constant in the same species. At first all are globose; as they mature, the majority are ovoid or elliptic; some are fusiform, with regularly attenuated extremities. In _Hygrophorus_ they are rather irregular, reniform, or compressed in the middle. Sometimes the external surface is rough with more or less projecting warts. Some mycologists are of opinion that the covering of the spore is double, consisting of an _exospore_ and an _endospore_, the latter being very fine and delicate. In other orders the double coating of the spore has been demonstrated. When the spore is coloured, the external membrane alone appears to possess colour, the endospore being constantly hyaline. It may be added here, that in this order the spore is simple and unicellular. In _Lactarius_ and _Russula_ the trama, or inner substance, is vesicular. True latex vessels occur occasionally in _Agaricus_, though not filled with milk as in _Lactarius_. [Illustration: FIG. 4.--_Polyporus giganteus_ (reduced).] POLYPOREI.--In this order the gill plates are replaced by tubes or pores, the interior of which is lined by the hymenium; indications of this structure having already been exhibited in some of the lower _Agaricini._ In many cases the stem is suppressed. The substance is fleshy in _Boletus_, but in _Polyporus_ the greater number of species are leathery or corky, and more persistent. The basidia, spicules, and quaternate spores agree with those of _Agaricini_.[L] In fact there are no features of importance which relate to the hymenium in any order of _Hymenomycetes_ (the _Tremellini_ excepted) differing from the same organ in _Agaricini_, unless it be the absence of _cystidia_. [Illustration: FIG. 5.--_Hydnum repandum._] HYDNEI.--Instead of pores, in this order the hymenium is spread over the surface of spines, prickles, or warts.[M] AURICULARINI.--The hymenium is more or less even, and in-- CLAVARIEI the whole fungus is club-shaped, or more or less intricately branched, with the hymenium covering the outer surface. [Illustration: FIG. 6.--_Calocera viscosa._] [Illustration: FIG. 7.--_Tremella mesenterica._]