. A handbook of cryptogamic botany. Cryptogams. CONFERVOIDE^ HETEROGAMY 225 formed at the side, through which the, colourless portion of the proto- plasm protrudes in the form of a papilla which takes up the antherozoids. In other cases the oogone splits in the same way as the ^?Oosporanges, throwing back a kind of lid ; through the lateral crevice exudes some colourless mucilage in the form of a beak-like canal, through which the antherozoids enter, and coalesce with the hyaline portion of the oosphere. Immediately after impregnation the oosperm inyests itself with a cell-wall, and assumes a
. A handbook of cryptogamic botany. Cryptogams. CONFERVOIDE^ HETEROGAMY 225 formed at the side, through which the, colourless portion of the proto- plasm protrudes in the form of a papilla which takes up the antherozoids. In other cases the oogone splits in the same way as the ^?Oosporanges, throwing back a kind of lid ; through the lateral crevice exudes some colourless mucilage in the form of a beak-like canal, through which the antherozoids enter, and coalesce with the hyaline portion of the oosphere. Immediately after impregnation the oosperm inyests itself with a cell-wall, and assumes a brown colour, still remaining within the oogone, which separates from the other cells of the filament, and falls to the ground, where the oosperm passes a period of rest before germir nation as a Fig. 202.—Bnlbochaic setigera. Ag. B, unicellular alltheridial plant. Ay C, young bicellular plajitSr Z> mature plant-with oogonei fJ, and ' dwarf male,'rf7« ( X 400). (After Cooke.) In some species the mode of fertilisation is more complicated. Peculiar .zoospores known as androspores are produced non-sexUally in special cells of the parent-plant, similar to those which give birth to th6 antherozoids, only that there is in their case no preliminary formation of ' special mother-cells.' These androspores, which closely resemble the antherozoids in form and size, fix themselves after swarming to a definite spot on the female plant, on or near an oogone, producing very small male plants, which are known as ' dwarf males' or micranires. Each of these consists of two or three cells, the uppermost of which is an antherid. This gives birth to one or more antherozoids, which escape Q. 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 Bennett, Alfred W. (Alfred William), 1833-1902; Murray, George Robert Mi
Size: 1843px × 1356px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookpublisherlondonnewyorklongm
