1408. The process of fermentation is that of putrefaction carried on in the air, or the polar process of fermentation. Both processes consequently observe a polar relation towards each other. 1409. The sugar-process passes over finally into acidification. 1410. The _Inflammables_, as the ætherial oils, balsams, and resins, are formed in the antagonism of the sugar or of the _acids_. Here also belong most of the peculiar vegetable matters, as the milky saps, colouring matters, medicinally active bodies, poisons, and the alkaloids. C. _Tracheal-processes._ a. _Leaf-process--Inspiration._ 1411. In the foliage the woody rings have issued freely into the air, in order that they may offer their whole surface to its influence, and thus become electrified and oxydized. 1412. The leaf is the free, external organ of respiration to the plant; it is its _lung_. Through the leaf the air, and chiefly its oxygen, is transferred into the plant, just as it is through the lungs into the animal. 1413. The leaves take in oxygen gas; this is their _essential_ function, and not that of exhaling it. 1414. The leaves _only_ exhale oxygen gas when exposed to light. The development of oxygen in the plant is accordingly a light-and not an air-process. In consequence of this the leaves give out oxygen gas only during the day, but during the night and even upon gloomy days, where not the light but only the air is active, they take in oxygen and give out carbonic acid. 1415. The light develops the oxygen gas out of the plant in a perfectly inorganic manner, like as from every water, that can be set in a process of tension. _Rumford_ has developed by simple glass tubes oxygen gas out of water. The oxygen gas of plants is therefore a result only of the decomposition of water in an inorganic manner by the agency of light, or virtually the separation only of the oxygen that is clinging to the water. 1416. Through the process of respiration in the plant carbonic acid has been formed and excreted. For the mucus becomes oxydized, and thereby the process also of fermentation, the product of which is carbonic acid, is promoted. 1417. The respiratory process of the leaves is the perfected process of fermentation in the stalk, in which finally, namely, in the fruit-saps, the separation of both the products of fermentation, the vinous and acetic, is prepared. 1418. Just as acids and sugar originate in the stalk, so in the foliage does their electrical antagonism, or the ætherial oils and perfumes. Sweet scents or perfumes are properties of the air, and therefore originate also with the aerial process. This is retrospectively a proof that the leaf-process is the respiratory process. 1419. Through the leaves, with which the whole surface of the earth is covered, the planet respires, and thereby the surface of the earth principally obtains its electricity.