. College botany; structure, physiology and economics of plants. Botany. 306 COLLEGE BOTANY grains) develop into very small three-celled Gametophytes, are carried by the •\\'i]id, some of them passing through the micropyle, where they come in contact with the macrosporangium. They develop tubes which grow through the nucellus, finally readiing the archegonia. During this time the generative cell enters the pollen tube and thence into the pollen chamber, divides into two cells, the stalk cell and the body cell. This body cell gives rise ,6b. Fig. 152.—(a) Cluster of Btaminale cones; (6) pollen
. College botany; structure, physiology and economics of plants. Botany. 306 COLLEGE BOTANY grains) develop into very small three-celled Gametophytes, are carried by the •\\'i]id, some of them passing through the micropyle, where they come in contact with the macrosporangium. They develop tubes which grow through the nucellus, finally readiing the archegonia. During this time the generative cell enters the pollen tube and thence into the pollen chamber, divides into two cells, the stalk cell and the body cell. This body cell gives rise ,6b. Fig. 152.—(a) Cluster of Btaminale cones; (6) pollen grain; (c) pistillate cone; (d) scale from pistillate cone showing two ovules. to two ciliate sperm cells which swim in the fluid of the chamber and finally reach the egg ceil of the archegonium. In comparison with the ferns, it will be noted that the number of sperms is few and that they never eeoap© from, the tube. The result of fertilization is the formation of a seed. The Finales includes the pine, larch, spruce, fir, cypress, arbor vitae, cedars and junipers. They are characterized by cone fruitsi and are freqtiently referred tO' as " ; However, in some of the species the cones are modified into ben-y-like fruits, such as are formed in the junipers. There are about 40. 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 Cook, Melville Thurston, 1869-1952. Philadelphia and London, J. B. Lippincott Company
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1920
