HERBARIUM, the name usually given to a collection of dried plants, intended for the future study and examination of botanists. For collecting plants, a box of tinned. iron, called a zaseulum, is generally used, which preserves most plants from withering.' for at least some hours. Plants intended for the herbarium should be collected on a dry day; plants which when gathered have moisture on their leaves should, when brought borne, be placed in a vessel of water, and there allowed to dry. Plants with thick succulent stems or leaves are immersed for a few seconds in hot water to kill them. The specimens are then laid between layers of blotting-paper, or of a thick bibulous kind of paper called botanical drying-paper, not spread out with anxious minuteness, nor so placed as to distort their parts. The number of sheets of paper in each layer is accommodated to the nature of the plants, and pressure is applied by means of weights, screws, or straps, the whole being inclosed in boards, and the layers of paper, when very numerous, having also boards occasionally interposed. Care must be taken that too much pressure be not applied at first, lest the parts of the plants be unfitted for future examination. For a short time, the paper is changed every day, or every second day, dry paper being supplied. Specimens have the best appearance which are quickly dried. Some plants which, in spite of all care, lose their natural colors in the ordinary method of drying, and become black, as orchids, may be beauti fully dried by inclosing the layers of paper in a network wire-frame, and hanging the package before a fire, where it is turned round like meat roasting. Specimens are thus
dried in a few hours, which otherwise would have required eight or ten days.—When the specimens are fully dried, they are laid within sheets of writing-paper, or they are gummed or glued to sheets of paper, the name of the species, with the locality, date of collection, and any other interesting particulars, being marked beside each. As much as possible of each plant is preserved in the herbarium, but the flower and leaf must always be exhibited. Sonic parts,of plants, as succulent roots, fruits, etc., are other wise preserved. The herbarium is arranged according to a botanical system. Care must be taken to preserve it from the ravages of moths and beetles by frequent inspec tion, by the aid of camphor, and by the occasional application of a little corrosive sub limate. There are herbaria in existence which are now some centuries old, and which are still consulted for the identification of species. The herbarium enables us to com pare plants which flower at different seasons, and those of different countries. The herbaria formed by travelers have been of great importance to the progress of botany.