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 phz- 
nogamous 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 unfrequently 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 (4). 
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 integument 
(2) of the ovule of Collomia coccinea. 'The epidermis- 
cells contain merely granules of starch. 
