. Botany for agricultural students . Botany. GAMBTOPHYTES 443 the young sporophyte until it becomes self-supporting. The female gametophyte therefore consists of many cells when mature and bears a number of archegonia on the portion exposed by the opening forced in the spore wall by the expansion of the game- tophyte. Previous to fertiUzation, the male gametophytes, each still, except for a small slit-Hke opening, encased in the wall of the. Fig. 395. — The gametophytes and young sporophyte of Selaginella. A, a megaspore containing a female gametophyte with the portion bearing the archegonia e
. Botany for agricultural students . Botany. GAMBTOPHYTES 443 the young sporophyte until it becomes self-supporting. The female gametophyte therefore consists of many cells when mature and bears a number of archegonia on the portion exposed by the opening forced in the spore wall by the expansion of the game- tophyte. Previous to fertiUzation, the male gametophytes, each still, except for a small slit-Hke opening, encased in the wall of the. Fig. 395. — The gametophytes and young sporophyte of Selaginella. A, a megaspore containing a female gametophyte with the portion bearing the archegonia exposed by the slit-like opening in the spore wall (X 100). B, section through a megaspore, showing the spore wall (w) and female game- tophyte (g) with one archegonium (o) with neck and egg (e) visible (X 100). C, a section through an antheridium, showing the small prothallial cell at the base and the wall cells which enclose the sperms within, one of which is shown fully mature at the left (X 500). D, a young sporophyte with stem at s and root at r and foot extending into the gametophyte which is still enclosed in the spore wall (m). From Atkinson and nature. microspore, fall out or are blown out of the microsporangia, which open when the spores are mature, and fall or are carried by the wind to the megasporangia where the female gametophytes are developing. Here the sperms escape, and reach the archegonia, which are accessible through the slit-like openings in the walls of the megasporangia and megaspores. The fertilized egg develops immediately irrto a sporophyte. Often the female gametophyte remains in the megasporangium until the weight of the young sporophyte tumbles it out. After the young sporophyte becomes. 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 Martin, John N. (John Nathan), b. 1875. New
Size: 1772px × 1411px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
