. Fundamentals of botany. Botany. 428 STRUCTURE AND LIFE HISTORIES contents of the nucellar tissue, thus faciHtating the passage of the delicate tube. The dissolved con- tents nourish the growing tube, which at first serves as a haustorium to absorb the nourishment. Thus the male (as well as the female) gametophyte, lives as a parasite upon the tissue of the sporophyte. Soon after the pollen-tube has begun to form, the tube-nucleus moves down toward the tip, where it remains, presiding over the subsequent growth of the tube (Fig. 318). At about this time, also, the antheridial mother-cell divi
. Fundamentals of botany. Botany. 428 STRUCTURE AND LIFE HISTORIES contents of the nucellar tissue, thus faciHtating the passage of the delicate tube. The dissolved con- tents nourish the growing tube, which at first serves as a haustorium to absorb the nourishment. Thus the male (as well as the female) gametophyte, lives as a parasite upon the tissue of the sporophyte. Soon after the pollen-tube has begun to form, the tube-nucleus moves down toward the tip, where it remains, presiding over the subsequent growth of the tube (Fig. 318). At about this time, also, the antheridial mother-cell divides, forming a wall-cell^ and a generative cell. In this condi- tion the first winter is passed. After pollination the carpellate scales, by growth, are brought close together, and secrete a very Fig. 318.—White pine . , . , , V. {Pinus Sirobus). Germi- sticky, resinous substance, all of :L!"sXSli: ^hich very completely excludes , generative cell; , any water from between the scales, tube-nucleus. X about „, ,, . , . 236. (After Margaret c. -The cone then mcreases greatly m Ferguson.) ^^^^ (Jjg ^og)_ 381. Fertilization.—Early in the following spring (May- June), the generative cell, after passing into the pollen- tube, divides to form two sperm-cells, and the pollen-tube continues its growth toward the archegonia. By this time (June) the egg lies mature within, and completely ' Also commonly called ";. 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 Gager, C. Stuart (Charles Stuart), 1872-1943. Philadelphia, P. Blakiston's son & co.
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Keywords: ., bookauthorgag, bookcentury1900, bookdecade1910, booksubjectbotany
