. The essentials of botany. Botany. FERN STRUCTURE 255 structures consisting of an outer layer of cells surrounding a central mass of small cells, each of which produces a sperm. When mature, the antherids rupture and permit the escape of the spiral multiciliated sperms which swim with a rotary motion. 452. The archegones are flask-shaped organs sunken into the tissues of the plant. At first the neck is closed, but at maturity it opens down to the egg. Fertilization takes place in water (after rains or heavy dews), the sperms swimming to and down the neck of the arche- Pm. isi.âPem aroh- , . .
. The essentials of botany. Botany. FERN STRUCTURE 255 structures consisting of an outer layer of cells surrounding a central mass of small cells, each of which produces a sperm. When mature, the antherids rupture and permit the escape of the spiral multiciliated sperms which swim with a rotary motion. 452. The archegones are flask-shaped organs sunken into the tissues of the plant. At first the neck is closed, but at maturity it opens down to the egg. Fertilization takes place in water (after rains or heavy dews), the sperms swimming to and down the neck of the arche- Pm. isi.âPem aroh- , . ., .. .,, egone, egg, antherid and gone, where one oi them unites with sperm, the egg. 453. Sporophyte. After fertilization the egg divides again and again, soon producing a solid stem from which a root springs at one end, while from the other the leaves arise. The latter are at first small and quite simple in structure, but those formed later are larger and more and more complex in structure, until finally the full form _^_ ._ . .^ is reached, and still later the full /â¢j^?^£====' (^^'^ size. The stem, bearing leaves >2]^' and roots, constitutes the sporo- ^^ ifofoi'-? pliyte, which is sharply contrasted ^^^ --vir'' with the gametophyte in structure, Fia. 132.âDevelopment of size, and duration, the latter being fern sporophyte. i t i i /⢠â i short-lived, small, and of simple structure, while the former is long-lived, often of large size, and of great complexity of structure. On this plant the spores are eventually produced which on germination give rise to gametophytes like those with which we started, thus completing the round of life. In most Ferns the spores are of one kind, only (isospores), but in a few they are of two kinds (heterospores) in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original wor
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisher, booksubjectbotany
