1432. The liber no longer conveys any sap to the divided tracheæ, solely because it has lost the condition to be affected by the light-polarity. On the contrary, a plant does not die so soon, if the liber be cut through, but the spiral vessels preserved. The spiral fibres conditionate consequently the motion and the excitation of the organic processes. 1433. _The spiral fibres are therefore, apart even from their function of respiration, or rather because this is the highest vegetable function, that for the plant, which the nerves are for the animal._ 1434. The tracheæ of plants do not ramify like the nerves of animals; but if they divide, they separate only as fascicles, which have been liberated from their origin. The tracheæ commence too directly in the mass of cells, wherever that may happen to be, and thus become what governs an organ, exactly like the animal nerves. Their analogy is greatest with the sympathetic nerves. The tracheæ, just as in the animal kingdom, are the mediators, not the founders, of vegetable life. 1435. The principle of motion must reside in the tracheæ, provided that higher, and not merely chemical movements, occur in the plant. 1436. These movements must and can only exist in those organs which consist almost entirely of spiral vessels, and thus only in the highest organs. 1437. Such are the leaves and the corollæ. Is it wished to compare the corolla, apart from its sexual relation, with an organ in animals, it can only be contrasted with the highest nervous organ. The corolla is the brain of plants, that which corresponds to light, but which here remains stationary upon the sexual stage. It may be said that what is sex in the plant, becomes brain in the animal, or the brain is only the animal sex. 1438. The most general function of the brain is, however, feeling or touch combined with motion. If the corolla could attain to a sensorial function, it would be to that of touch. 1439. It is conducted thereto; but at the instant, when it is indulged in feeling the mental capacity of the animal, it sinks down exhausted and dies. It is punished for the risk that has been run in wishing to attain unto self-cognition. 1440. Motion and touch are revealed only in the highest organs of the plant, or in the stamina. The filament moves upon the pistil and touches it with the pollen, which at that instant, however, is scattered in small particles, and leaves behind the filament in a withered state. 1441. The motion performed by the filaments appears to be a simple operation of the irritability in the tracheæ that have become soft, without undergoing chemical decomposition, but probably by sudden influx of sap, induced by the tension of air in the spiral vessels.