. Botany for agricultural students . Botany. GAMETOPHYTE 433 swimming sperms (Fig. 385). The chimney-shaped archegonia are near the notch of the prothallus, and the globular anther- idia are in the region of the rhizoids. In some Ferns the male and female sex organs are on different gametophytes. The sperms are active swimmers and reach the egg by swim- ming down the neck of the archegonium which, like the arche- gonia of Bryophytes, opens at the top when the egg is ready for fertilization. From the neck of the archegonium, a substance is also discharged, which chemically attracts the
. Botany for agricultural students . Botany. GAMETOPHYTE 433 swimming sperms (Fig. 385). The chimney-shaped archegonia are near the notch of the prothallus, and the globular anther- idia are in the region of the rhizoids. In some Ferns the male and female sex organs are on different gametophytes. The sperms are active swimmers and reach the egg by swim- ming down the neck of the archegonium which, like the arche- gonia of Bryophytes, opens at the top when the egg is ready for fertilization. From the neck of the archegonium, a substance is also discharged, which chemically attracts the Fig. 387. —• A diagram of the life cycle of a Fern. A, sporoph3rte bearing sori in which the sporangia occur. B, a gametophyte, a product of a spore and the generation bearing the gametes, the sperms of which are shown passing from the antheridia to the archegonia. C, gametophyte bearing a sporophyte, which soon becomes independent and like the one at A. The fertilized egg immediately grows into a sporophyte, which lives on the gametophyte only until it has roots and leaves sufficiently developed to support itself {Fig. 386). After the sporophyte reaches maturity, sori are developed and the life cycle is completed {Fig. 387). Among a group of gametophytes one usually finds sporophytes in various stages of development and greenhouse attendants sometimes collect and pot the young sporophytes growing in unfavorable places, so that they mature and thereby increase their stock of Ferns. Usuallj^, however,. 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 York : John Wiley & Sons, Inc.
Size: 1632px × 1532px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
