1518. The asexual plants have no true root, stalk, and leaf; they have not even a true bark, liber, and wood, in so far as these first make their appearance through separation. Tracheæ are first exhibited in the higher ferns, and then only as constituting a single string, which occupies the middle of the plant, and consequently forms no circle or zone.
1519. As again the true seed is a leaf-formation, and possesses therefore cotyledons or seed-lobes, such seeds must be wanting in the asexual plants; they are therefore Acotyledones. From the same cause, however, the germinal leaves or plumula must be also wanting; they are therefore germless, or anembryonic.
1520. The farinaceous or granular matter, lying next to the germ when within the shell of the true seeds, is called the albumen or perisperm; the seeds of the asexual plants are therefore nothing else but albumen. They are therefore devoid of the funiculus or, what has been called, umbilical cord.
1521. The involucre, wherein, in true seeds, the germ and albumen are found, is the seed-coat or testa; consequently what has been called the capsule of the asexual plants (of mosses and ferns) corresponds simply to this spermoderm or seed-covering, and is no true ovarium. The capsules of mosses and ferns are therefore seeds full of albuminous dust.
1522. If any of these be regarded as a capsule, it can be the calyptra of the mosses. This, too, is probably nothing else than the external testa; the proper capsule being its internal coat.
1523. The indusium of ferns incloses several capsules as they have been called, or properly seeds, and might therefore, if considered alone, be compared with an ovarium, but it is probably none other than the covering corresponding to the perichœtium that surrounds the base of the setæ in mosses. The sorus is an accumulation of seeds with pulverulent albumen contained in a membranaceous covering, the indusium.
1524. The life of the asexual plants consists simply in the galvanic process. They are the primary organisms, planted in air.
1525. As being simply galvanic process, they would require but little light and air; they therefore seek the darkness, like the roots, and thrive also in a corrupt atmosphere, in caves, mines, cellars, and such like situations. They can from the same cause thrive only in moisture, in water, upon marshy meadow lands, after rain, copious dew, and so on.
1526. They are devoid the process of fermentation, as being that which is imparted by the oxydation of air, and they therefore yield neither sugar nor acids. They are simply the organized process of putrefaction; their ultimate product is therefore germinal powder, infusorial matter. Their remaining secretions are alkaline bodies; to which belong the pungent, fetid, and nauseous excretions, as the hydrogen gas and ammonia of the fungi, the mucus of the fuci, the carbonate of lime in the lichens, the cell-threads of the mosses, the fetid principle of ferns.
1527. Very few of these plants require the course of a summer in order to perfect or complete the vital course; a single ray of light of one day's, aye, of one hour's duration, is sufficient with most of them to evoke the feeble difference, to rouse the swell of the sap, and precipitate the infusorial powder.