EXPLANATION OF THE PLATES. 267
Fig. 24, A very young leaf of Crassula portulaca, the five cells which solely compose it being still surrounded by a parent-cell.
25. Three cells from an articulated hair of potato, with a retiform current of mucus upon their walls. In the central cell the direction of the currents is par- tially indicated by arrows.
In all the instances in which I have observed the movements in the cells of phænogamous plants, I have constantly found the moving matter to consist of a yellowish mucous fluid, perfectly insoluble in distilled water, and mixed with minute black granules, but differing entirely from the other aqueous sap of the cells; and even when the currents were so small as to appear merely as excessively minute delicate lines of black points, I sueceeded with higher magnifying powers in distinguishing the yellowish mucous fluid, especially when aided by the favorable circumstance (which not unfrequentiy occurs) of the current becoming arrested by some impedi- ment, which causes a somewhat larger quantity of the moving material to accumu- late, and is generally followed either by a change in the direction, or a division of the current.
PLATE II.
Fig. J. Cells from the epidermis of the pericarp of Ocymum | basilicum, moistened with water, so that the mucous globule has expanded, and torn the outer cell-wall (a) from the side walls (0).
2. Cells from the pericarp of the epidermis of Ziziphora dasyantha.
3. Cells from the pericarp of the epidermis of Salvia ver- ticillata.
4, Cells from the pericarp of the epidermis of Salvia Horminum.
5. Cells from the pericarp of the epidermis of Salvia Spielmanni.
2, 3, 4 and 5, a, exhibit the remains of the side-walls of the ruptured cells.
6. A portion of the epidermis (a) and of the imtegument (2) of the ovule of Collomia coccinea. 'The epidermis- cells contain merely granules of starch.
