to the earth mixed up with the black liquid into which these ultimately resolve themselves. Sometimes the _whole_ external surface of the fungus is dusted with seed; but much more frequently they are restricted to some particular part, and either lie on the upper side, as in the _Pezizæ_, or on that which is beneath, as in the mushroom. The spores generally lie on the outside of the fungus, but in the puff-ball, as every one knows, they are internal, and in such prodigious quantity as sometimes entirely to fill its cavity. It is a speculation from Germany, that spores are capable of altering their forms, and that according to the accidents of climate or soil, they assume this or that type, and give rise at different times to different kinds of funguses; on which it is sufficient to remark, that while there is not the least foundation for such an hypothesis, there is in fact much evidence against it; nature acts by immutable laws and has no changelings. To appeal to experience, when did mushrooms ever spawn toadstools? When was the _Pietra funghaia_ ever seen to bring forth anything but its own Polyporus? or the fig, the poplar, or the hazel (when singed and watered to render them prolific) exhibit any but their own particular mushroom? Spores are endowed, like other seeds, with an extraordinary vitality, which may lie dormant in them for an indefinite period; but unlike most other seeds, they seem capable of resisting the prolonged heat of boiling water, infused in which, and poured upon the ground, they are still capable of producing each after its kind. The specific gravity of spores is greater than that of water, as may be seen by placing a mushroom over a glass which contains it, when, falling upon the surface, they presently subside to the bottom. These spores sometimes merely multiply without any further progress in development; sometimes they proceed a certain way only, and then, the conditions necessary for their further advance failing, this is arrested; sometimes, as in the _Sistotrema_, the plant _appears twice_ under a _perfect_ form, being for part of its existence a _Hydnum_, and during the other half a _Boletus_; but, generally speaking, these minute corpuscular bodies are destined to receive an infinite variety of protean and imperfect forms, and to pass stage by stage, and step by step, to the full attainment of that ultimate one which they assume when their growth has reached its natural limits. Sometimes the spore expands outright into a puff-ball; sometimes it shoots up straight into a club, as in some of the Clavarias; or lies like a bowl, resupinate on the ground and stalkless, as in the _Peziza_; in other cases, it assumes the more perfect but much less simple forms of _Chanterelle_, _Boletus_, _Dædalea_, _Morel_, or _Mushroom_. DEVELOPMENT OF SEEDS.