The New Student's Reference Work/Secretion

Secre′tion (in plants), in its broadest sense, the process by which substances are separated from the protoplasm; also the substances so separated. In this sense the cell-wall and starch-grains are secretions, since they are formed by the protoplasm and separated from it. The term is usually applied, however, to waste products (sometimes distinguished as excretions) or to products which have some special function, e. g., enzymes (q. v.) and nectar. The number and variety of secretions are very great. Some are formed in a special cell or group of cells, constituting a gland, which may be on the surface (e. g., in geranium leaves) or may adjoin an internal space into which the secretion is poured (e. g., resin-glands of pines). In other cases the secretion accumulates in the gland-cells, which finally die, leaving a mass of the secretion occupying their room, e. g., in orange-rind. The methods by which the secretion is put forth from a cell are not known.