Various solvents, such as benzene, alcohol and chloroform, will dissolve out the pigment, leaving the plastid colorless.
More emphasis is, however, now laid on the action of the plastid in polymerization, while the initial stages are still not definitely ezplaincd.
Whether the formation of the starch grain is due to a secretion from the plastid (Meyer, 1895) or to a direct transformation of the proteid of the plastid (Timberlake, 1901) has not been definitely established.
The formaldehyde at once undergoes a process of condensation oi- polymerization by the protoplasm of the plastid, while the hydrogen peroxide is said to be decomposed into water and free oxygen by another agency in the cell, of the nature of one of the enzymes of which we shall speak later.
In some cases the plastid disappears and the crystalline pigment only is left.
With nucleolus and plastid ~.
The Metazoa all commence their individual existence as a single cell or plastid, which multiplies itself by transverse division.
The working of it is not at all completely understood at present, nor can we say exactly what is the part played by the pigment and what is the rfile of the protoplasm of the plastid.