Archegonium

“ The first wall in the embryo is nearly at right angles to the axis of the archegonium and divides the egg cell into nearly equal parts. This is followed by nearly vertical walls in each cell (Fig. 62, A) . Very soon a two-sided apical cell (Fig. 62, B, a) is formed in the upper half of the embryo, which persists until the embryo has reached a considerable size. As in the liverworts the young embryo is completely covered by the growing archegonium wall. ”

“ An archegonium consists of a large oval egg-cell surmounted by a short neck composed of one or more tiers of cells, six to eight cells in each tier. Before fertilization the nucleus of the egg-cell divides and cuts off a ventral canal-cell; this cell may represent a second egg-cell. The egg-cells of the archegonia may be in lateral contact (e.g. Cupressineae) or separated from one another by a few cells of the prothallus, each ovum being immediately surrounded by a layer of cells distinguished by their granular contents and large nuclei. ”

“ From the fertilized egg within the archegonium the ordinary leafy fern-plant arises. When in other plant-groups the prothallium ceases to be independent, as in seed-plants, it often retains the name. For example, many would speak of the female gametophyte (endosperm) found in seeds as a female prothallium. ”

“ The sperm-cells escape from the antheridium and in the water that collects on the prothallus are carried to the archegonium, where fertilization of the egg takes place. From the fertilized egg-cell a plant grows, becoming a “fern.” In most cases the prothallus soon dies. The prothallus is the gametophyte (from Greek, signifying the fertilized plant) .
The fern plant, arising from the fertilized egg in the archegonium, becomes a perennial plant, each year producing spores from its fronds (called the sporophyte) ”

“ The entire structure of the archegonium, with its neck and canal-cells, has disappeared, and nothing is left but the indispensable oosphere. When the oosphere has been fertilised, and has commenced the cellular divisions which lead to the formation of the embryo (Fig. 255) , the synergidæ and antipodal cells are absorbed, and a cell-formation begins by a new process which emanates from the definitive nucleus and by which a parenchymatous cell-tissue, the nutritive-tissue, arises which may perhaps be considered as homologous with the endosperm of the Gymnosperms. ”

“ The female organ (archegonium) and the cell which it produces are practically identical in both cases. Fossil remains have shown that some of the plants like Selaginella which flourished in Palæozoic times seemed to have come very near to the production of seed. Thus one species which has been described shows a megaspore which was permanently within the sporangium, and which in its general development greatly resembled a fruit. ”

“ Wet rocks, N. Eng. to S. C.; more common in the mountains.
3. LEJEÙNEA, Libert. (Pl. 24.)
Leaves decurrent at the folds, the lower lobe incurved and ventricose; underleaves usually present, entire or bifid. Archegonium with a slender persistent style, solitary on a usually very short branch; the perianth free from the involucral leaves, oval or oblong, terete or angular, variously carinate, cristate, or ciliate. Capsule globose, 4-cleft to the middle, the valves recurved. Spores large (40–50 μ broad) , globose or oblong, tuberculate. ”

“ The neck of the archegonium is quite long, but does not project above the surface of the prothallium (Fig. 77, H) .
The pollen spores are produced in great numbers, and many of them fall upon the female flowers, which when ready for pollination have the scales somewhat separated. The pollen spores now sift down to the base of the scales, and finally reach the opening of the ovule, where they germinate. No spermatozoids are produced, the seed plants differing in this respect from all pteridophytes. ”

“ Veins are never found in the leaves.
The ventral part of the archegonium (calyptra) continues to grow for some time, and encloses the growing embryo, but when the spores are ripe it is finally ruptured by the sporangium, and remains situated like a sheath (vaginula) around its base. The sporangium opens, longitudinally, by valves or teeth (Fig. 194, 195, 197 b) , very rarely by a lid, or sometimes not at all. A columella is wanting (except in Anthoceros, Fig. 194) ; but on the other hand, a few of the cells lying between the spores are developed into elaters (Fig. 196) , i.e. ”

“ H, short branch containing the young sporogonium, × 4.
When very young the archegonium is composed of an axial row of three cells, surrounded by a single outer layer of cells, the upper ones forming five or six regular rows, which are somewhat twisted (Fig. 54, A, B) . As it becomes older, the lower part enlarges slightly, the whole looking something like a long-necked flask (C, D) . The centre of the neck is occupied by a single row of cells (canal cells) , with more granular contents than the outer cells, the lowest cell of the row being somewhat larger than the others (Fig. 54, C, o) . ”

“ One of the Liverworts Griffith described may be taken as an illustration to this part of our subject on account of the interest of its re-discovery and re-description in 1910 by Goebel. This is a plant collected in Assam and named Monosolenium tenerum. This Marchantiaceous plant is described as having no air-chamber layer, as bearing sessile, dorsal, antheridial receptacles, and terminal, shortly stalked archegoniophores with one ventral groove in the stalk. A single archegonium—later capsule—is found in each of the half-dozen involucres. ”

“ The reproductive organs ultimately produced on the same or on different individuals are of two kinds, the antheridia and archegonia; the origin of both is from single superficial cells of the prothallus. The antheridium (fig. 8) at maturity consists of a layer of cells forming the wall which encloses a group of small cells; from each of the latter a single motile spermatozoid originates. The archegonium (fig. 9) consists of a more or less projecting neck and the venter, which is usually enclosed by the tissue of the prothallus. ”

“ The embryo is forced more or less into the endosperm [247] in which it may rest for a longer or shorter time, and generally is developed to such an extent that it has a distinct primary-root (radicle) and stem (plumule) with one or more embryo-leaves (cotyledons) .
When the oosphere has been fertilised its nucleus sinks down to its lower end, and by repeated division into two, forms four cells lying in one plane (Fig. 253, see base of the left archegonium) . ”

“ It is filled with a colorless tissue, the prothallium, and if mature, with care it is possible to see, even with a hand lens, two or more denser oval bodies (ar.) , the egg cells of the archegonia, which here are very large. The integument is not entirely closed at the top, but leaves a little opening through which the pollen spores entered when the flower was first formed.
After the archegonia are fertilized the outer parts of the ovule become hard and brown, and serve to protect the embryo plant, which reaches a considerable size before the sporangium falls off. ”

“ The apex of the stem or of certain branches is adapted for the formation of female shoots. The archegonia are most frequently aggregated on the apex of the shoots, and are encircled by their leaves (perichætium) . Between these and the archegonia, enclosing the latter, a peculiar cup-shaped organ (the involucre) is formed. This group only includes leaf-bearing genera: Frullania, Radula, Madotheca, Ptilidium, Calypogeia, Lepidozia, Mastigobryum, Lophocolea, Jungermannia, Scapania, Plagiochila. ”

“ After a time, however, the cells are produced transversely as well as longitudinally, resulting in the formation of a flattened leaf-like expansion (Fig. 125, d) , a cellular structure, the so-called Prothallus, which can scarcely be distinguished from a young Marchantia. In this Prothallus are developed Archegonia and Antheridia: the union of the embryo-cell of the Archegonia and the spiral filament of the Antheridia gives rise to the new Fern, which may be seen growing out of the Prothallus (Fig. 126) , which soon passes away. ”

“ The female plants (Fig. 66, F) are always comparatively large and regularly heart-shaped, occasionally reaching a diameter of nearly or quite one centimetre, so that they are easily recognizable without microscopical examination.
All the cells of the plant except the root hairs contain large and distinct chloroplasts much like those in the leaves of the moss, and like them usually to be found in process of division.
The archegonia arise from cells of the lower surface, just behind the notch in front (Fig. 66, F, ar.) . ”

“ The organs mentioned here, antheridia and archegonia, are present in the Cryptogams (Pteridophyta) and the Gymnosperms. They have always the same fundamental structure, but with slight modifications of detail. These plants are therefore known as the Archegoniata. ”

“ The female prothallium may consist of many cells with well-developed archegonia, as in the Gymnosperms, or of only a few cells with the female organ reduced to the oosphere, as in the Angiosperms. In either case it is the product of the germination of a megaspore (embryo-sac) which is not shed from its sporangium (ovule) : hence it never becomes an independent plant, and was long regarded as merely a part of the sporophyte until its true nature was ascertained, chiefly by the researches of Hofmeister, who first explained the alternation of generations in plants. ”

“ On these are borne the sexual reproductive organs, the female known as archegones, the male as antherids. From the fertilization of the oösphere of the archegone by spermatozoids produced in the antherids, the asexual phase (sporophyte) of the plants is developed; this phase is represented by an ordinary fern, lycopod or horsetail.
This subkingdom comprises about 6,000 living species, of which more than three-fourths are confined to tropical regions. The number of extinct species known probably exceeds those living. ”

“ It has oblong-oval floating leaves 4–6 ́ ́ long, closely pinnately-veined, which bear conceptacles and branching plumose fibres on their under surface.
Subclass II. CELLULAR ACROGENS, or BRYOPHYTES.
Plants composed of cellular tissue only. Antheridia or archegonia, or both, formed upon the stem or branches of the plant itself, which is developed from the germinating spore usually with the intervention of a filiform or conferva-like prothallus.—Divided into the Musci, or Mosses, and the Hepaticæ. ”

“ The female or archegonia are much like those in the ferns, and the antheridia or male are also, as in the ferns, minute globular organs in which are the male cells. The branches bearing males are greenish, yellow, or even reddish, quite unlike the ashy gray foliage leaves which give to sphagnum its characteristic ashy gray color. Unlike the ferns, the male cells of sphagnum have only two tails, but they nevertheless swim, tail first, to the female, when the time for fertilization comes. ”

“ While some of the inferior Hepaticæ or Liverworts, severally consist of little more than a thallus-like frond, among the higher members of this group, and still more among the Mosses and Ferns, we find a distinctly marked stem. [8] Some Archegoniates (or rather Rhizoids) have foliar expansions that are indefinite in their forms; and some have quite definitely-shaped leaves. Roots are possessed by all the more-developed genera of the class; but there are other genera, as Sphagnum, which have no roots. Here the fronds are formed of only a single layer of cells ”

“ Making a great advance among the Archegoniates, this physiological integration reaches its climax among Phænogams. In them we see interdependence throughout masses that are immense. Along with specialized appliances for support and transfer, we find an exchange of aid at great distances. We see roots giving the vast aërial growth a hold tenacious enough to withstand violent winds, and supplying water enough even during periods of drought; we see a stem and branches of corresponding strength for upholding [294] the assimilating organs under ordinary and extraordinary strains ”

“ The inflorescence in agrimony is a raceme, in Poterium a dense-flowered spike, in Spiraea a number of cymes arranged in a corymb. The parts of the flowers are arranged on a 5-merous plan, with generally considerable increase in the number of stamens and carpels. The shape of the thalamus or floral receptacle, and the relative position and character of number of the stamens and carpels and the the fruit, vary widely and form distinguishing ”

“ The elegant little bark which thus plays with the current is no work of human hands, but a child of Nature: it is the Argonaut, whose tribes, decked in a thousand brilliant shades of colour, are wanderers of the night in innumerable swarms on the ocean's surface.
The marine shell which Linnæus called the Argonaut enjoyed great renown among the ancient Greeks and Romans. It was the subject of graceful legends; it had inspired great poets; it occupied the attention of Aristotle, who called it the Nautilus and Nauticos, and of Pliny, who called it Pompylius. ”

“ Archeius is the highest, exalted, and invisible spirit, which is separated from bodies, is exalted, and ascends, the universall occult nature, operator, and Physitian in all things. So Archiatrus is the supream Physitian of Nature, which distributes to every thing and every member their peculiar Archeius occultly by Ares. ”