1397. The bodies absorbed must move in the cells; for chemical solution and mixture, being itself nothing else than separation and union of atoms, is consequently motion. In a single cell the motion must be upon all sides, because the atoms are attracted and repelled from all points of the cell-wall. In cells, however, which are united with others and therefore subjected to longitudinal polarity, this motion must be performed in accordance with the axis of the cells. 1398. This motion proceeds to and fro, because the extremities of the cells have different polarities, and therefore repel the same atoms, which they have before attracted. In the cells the mucus appears to be converted into starch-granules. B. _Vascular Processes._ a. _Vessel-process--Conveyance of Sap._ 1399. The vessels or intercellular passages conduct the sap, or the water of the plant. Their function is therefore the continued conveyance of the sap that has been absorbed from the root, and rendered solid or consistent by the evaporation going on in the bark and elaborated by the cells. 1400. The vessels of plants are notwithstanding to be compared with the lymphatic vessels of animals, in so far also as these are distributed throughout the whole body, and convey the sap simply in one direction not in a circle. 1401. As the passages between all the cells are in all directions, so the vegetable saps or fluids flow in all directions, and not to one centre as in the animal. Plants have no heart. The sap pursues a tolerably rapid course in the vessels. A fading or drooping cabbage, two feet in length, can gradually become erect in a few minutes after being put to soak in water. In other respects the course of the sap in the vessels may be seen in many plants under the microscope. b. _Liber-process--Mixture of Sap._ 1402. In the liber, as being the mass of intercellular passages, the sap contained in the vessels principally accumulates, as in the thoracic duct of animals; in it the matters have not been simply conveyed and dissolved, but also mixed and converted into true vegetable sap, into blood. 1403. The tubes of the liber are those by which the chemical life is sustained. c. _Stalk-process--Secretion._ 1404. The stalk is the root planted in air, and consequently its process is the differenced process of putrefaction, in which the mucus becomes further evolved. 1405. The analysis chiefly occurs in the stalk; the mucus, or rather the starch, becoming converted into sugar and acids. 1406. Sugar is the mucus of the stalk, and is found in every vegetable sap, especially that of such plants as are characterized by the systems of the stalk, and have not yet attained the formation of the reticular leaf, as the Monocotyledones, e. g. the grasses. 1407. The sugar originates from a process of fermentation; the process of the stalk must consequently be regarded as a vital _process of fermentation_.