. Nature and development of plants. Botany. 368 GAMETOPHYTE OF FINALES of the nucleus of the megaspore, the gametophytic tissue being developed at a later period. You have noticed that there is no chamber formed above the archegonia, and it would be a natural inference that the male gametophyte must be of a somewhat different character from that of the cycads in order to met this. roc Fig. 253. Megasporangia of pine: A, scale-like outgrowth of sporophyll bearing two sporangia. B, section of A, taken through one of the sporangia, showing a small bract, o', and large scale-like outgrowth which b
. Nature and development of plants. Botany. 368 GAMETOPHYTE OF FINALES of the nucleus of the megaspore, the gametophytic tissue being developed at a later period. You have noticed that there is no chamber formed above the archegonia, and it would be a natural inference that the male gametophyte must be of a somewhat different character from that of the cycads in order to met this. roc Fig. 253. Megasporangia of pine: A, scale-like outgrowth of sporophyll bearing two sporangia. B, section of A, taken through one of the sporangia, showing a small bract, o', and large scale-like outgrowth which bears the sporangia, sp. The sporangium is surrounded by an integument, i, and con- tains a single megaspore, m, as in the Cycads. mc, microspores that have been drawn through the micropyle to the sporangium, into which their tube cells are growing. C, section of megasporangium enlarged and diagrammatic showing the female gametophyte at the time of fertilization—g, female gamet- ophyte, showing two archegonia with large female gametes, /g. At the left the tube of the microspore, mc, has entered the neck of the archegonium and the two male gametes have been discharged into the large sac of the female gamete. On the right the tube cell with male gametes is seen approaching the neck of the archegonium. i, integument; sp, remains of sporangium not disorganized by the gametophyte; t shows the disorganization caused by the tube cells as they grow towards the 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 Curtis, Carlton Clarence, 1864-1945. New York, H. Holt
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