. The Bible and science. Fig. 39.—Pollen grains of buttercupon the stigma, with their tubesextending—both very much en-larged. cellular tissue of the style until it comes in contactwith the ovule, which it enters at the foramen, just 90 THE SEED-THE EMBRYO. as we have seen to be the case in it reaches the embryo sac, the latter dividesand subdivides, forming numerous cells, which graduallyarrange themselves so as to form the embryo or youngplant which is contained in the seed. This is now ripe for growth, and, whenever it isplanted in a proper soil, with warmth and moisture,.
. The Bible and science. Fig. 39.—Pollen grains of buttercupon the stigma, with their tubesextending—both very much en-larged. cellular tissue of the style until it comes in contactwith the ovule, which it enters at the foramen, just 90 THE SEED-THE EMBRYO. as we have seen to be the case in it reaches the embryo sac, the latter dividesand subdivides, forming numerous cells, which graduallyarrange themselves so as to form the embryo or youngplant which is contained in the seed. This is now ripe for growth, and, whenever it isplanted in a proper soil, with warmth and moisture,. Fig. 40.—Longitudinal section of ovule of heartsease, a. Vascular bundle, coat. c. Inner coat. d. Nucleus, e. Embryo sac, with the germinalvesicle at its small end. /. Micropyle. g. End of pollen tube—very muchenlarged. it begins to sprout, and produces a plant like its the seed contains the embryo or youngplant alone, but usually it also contains a quantityof nutritive matter sufficient to supply the wants ofthe young plant until it has reached that point ofgrowth at which it is capable of drawing nourishmentfrom the soil. IRRITABLE STAMENS. 91 In all cases, it is necessary that the pollenshall unite with the ovule, in order that it may de-velop into the seed containing the embryo or youngplant. To secure this, numerous contrivances areprovided by nature. We have, first of all, the stickyfluid on the surface of the stigma, which will preventany pollen grain that has once touched it from fallingoff. The pollen grains, being light, may be carriedby the wind
Size: 1127px × 2217px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectnaturalhistory, booky
