. A text-book of botany for secondary schools. Botany. FLOWERS AND INSECTS 245 During the day the small female Pronuba rests quietly within the flower, but at dusk becomes very active. She travels down the stamens, and resting on an open pollen sac scoops out the somewhat sticky pollen with her front legs (Fig. 239, A). Holding the little mass of pollen against her body, she runs to the ovary, stands astride one of the furrows, and piercing through the wall with her ovipositor deposits an egg in an ovule. After depositing several eggs in this way, she runs to the top of the ovary and begins to
. A text-book of botany for secondary schools. Botany. FLOWERS AND INSECTS 245 During the day the small female Pronuba rests quietly within the flower, but at dusk becomes very active. She travels down the stamens, and resting on an open pollen sac scoops out the somewhat sticky pollen with her front legs (Fig. 239, A). Holding the little mass of pollen against her body, she runs to the ovary, stands astride one of the furrows, and piercing through the wall with her ovipositor deposits an egg in an ovule. After depositing several eggs in this way, she runs to the top of the ovary and begins to crowd into the funnel- shaped stigmatic cavity the mass of pollen she has collected (Fig. 239, B). These actions are re- peated several times, until many eggs have been deposited and repeated pollination has been effected. As a result of this, seeds are formed which develop abundant nourishment for the moth larvae, which become mature and bore their way out through the wall of the capsule (Fig. 240). 147. Cross-pollination.—In those flowers in which cross- pollination is the rule, self-pollination is hindered in a variety of ways. In the cases about to be considered, stamens and carpels are together in the same flower; of course, in dioecious plants there can be no such thing as self-pollination. It is necessary to remember also that when the stigma is ready to receive the pollen, it excretes upon its surface a sweetish, sticky fluid, which holds and feeds the pollen, inducing the development of pollen Fig. 240.—A mature capsule of Yucca, showing perforations made by larvee of Pronuba in escaping. — After Riley and 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 Coulter, John Merle, 1851-1928. New York, D. Appleton
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