in Natural History, a name given by Count Marsigli to a very remarkable species of marine substance, which he denominates a plant. It is tough and firm in its structure, and in many things resembles the common fucus; but instead of growing in the branched form which the generality of these substances assume, it is round and hollow, and in every respect resembles the shape of an orange. It has, by way of root, some exceedingly fine filaments, which fasten themselves to the rocks, or to shells, stones, or any thing else that comes in the way. From these there grows no pedicle; but the body of the orange, as it is called, is fastened by them to the rock, or other solid substance. The orange itself is usually about three or four inches in diameter; and whilst in the sea it is full of water, which it retains even when taken up. In this state it frequently weighs a pound and a half; but when the water is let out, and it is dried, it becomes a mere membrane, weighing scarcely any thing. It is best preserved by stuffing it with cotton as soon as the water is let out of it, and then hanging it up to dry. Its surface is irregular and rough, and its colour is a dusky green on the outside, and a clearer but somewhat bluish green within; and its thickness is about an eighth part of an inch. When viewed by the microscope, it is observed to be all over covered with small glandules, or rather composed of them; for they stand so thick one by another, as to leave no space between, and seem to constitute the whole substance; so that it appears very like the rough shagreen skin used to cover toys. These are indeed so many hollow ducts, through which the sea-water finds a passage into the globe formed by this skin, and by this means it is kept always full and distended. On cutting it with a pair of scissors, the water immediately runs out, and the skins collapse; but there is something extremely remarkable in this, for the whole substance, near the wounded place, is in motion, and seems as if alive, and sensible of the wound. The glandules are found full of water, resembling small transparent bottles; and what goes to the structure of the plant besides these, is an assemblage of a vast number of filaments, all of which are likewise hollow, being filled with a clear and transparent fluid.