Among the various helps towards acquiring a knowledge of the anatomy of plants, one of the principal is the art of reducing to skeletons leaves, fruit and roots; that is, of freeing them from their soft, tender and pulpy substance, in such a manner, that one can survey alone their internal, harder vessels in their entire connexion. This may be done by exposing the leaves to decay for some time soaked in water, by which means the softer parts will be dissolved, or at least separated from the internal harder parts, so that one, by carefully wiping, pressing and rinsing them, can obtain the latter alone perfectly entire. One will possess then a tissue composed of innumerable woody threads or filaments, which, in a multiplicity of ways, run through and intersect each other. By sufficient practice and caution one may detach, from each side of a leaf, a very thin covering, between which lies a delicate web of exceedingly tender vessels. These form a woody net-work, between the meshes of which fine glandules are distributed. This net is double, or at least can be divided lengthwise into halves, between which may be observed a substance that appears as it were to be the marrow of the plant. Persons who are expert often succeed so far, with many leaves, as to separate the external covering on both sides from the woody net, and to split the latter into two, so that the whole leaf seems to be divided into four. One might conjecture that this method of reducing leaves to skeletons must have been long known, as one frequently finds in ponds leaves which have dropped from the neighbouring trees, and which by decomposition, without the assistance of art, have been converted into such a woody net-work, quite perfect and entire. It is however certain that a naturalist, about the year 1645, first conceived the idea of employing decomposition for the purpose of making leaf-skeletons, and of assisting it by ingenious operations of art.