This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1909 Excerpt: ...are formed. Each of these may be compared to a female sea-urchin, for it forms within itself a little egg cell which must be fertilized if it is to develop into a new individual. The stamen is a long filament with an anther at the top. The anther gives rise to the pollen grains. These grains are so tiny that they are ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1909 Excerpt: ...are formed. Each of these may be compared to a female sea-urchin, for it forms within itself a little egg cell which must be fertilized if it is to develop into a new individual. The stamen is a long filament with an anther at the top. The anther gives rise to the pollen grains. These grains are so tiny that they are easily Mown about by the wind to fall perhaps on the sticky surface of the stigma. Each little pollen grain may be compared to the male sea-urchin, for it forms within itself a sperm cell. The sperm cell, like that of the sea-urchin, is irregularly shaped and develops a tail. The tail is of no use for swimming because it is not surrounded by water and it is held fast by the sticky surface of the stigma; but by means of it the nucleus of the sperm cell reaches the egg cell. The tail, or pollen tube, grows longer and longer until it reaches down the style to the ovary; the nucleus of the cell then works its way down through the tube, punctures and enters the egg cell and unites with the nucleus which it finds there (Fig. 59). This is the process of fertilization. The new cell, like the fertilized egg of the sea urchin, can now divide and the new cells can differentiate. The process of differentiation continues until a tiny new plant called a seed is formed. Fig. 59.--Diagrammatic section of a flower, showing a pollen grain sending a pollen tube down to the ovule. C, calyx; Co, corolla; a, anther, and /, filament, of the stamen; 0, ovary surmounted by -, style, and et, stigma; p, pollen grains, some in the anther, others on the stigma; iV, ovule; Et germ cell; pf, pollen tube penetrating the style and reaching the germ cell through an opening (the micropylej into the ovnle. Under proper conditions this is able to unfold itself into a plant li...
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Fine. Trade paperback (US). Glued binding. 238 p. Contains: Illustrations, black & white. Intended for a juvenile audience. In Stock. 100% Money Back Guarantee. Brand New, Perfect Condition, allow 4-14 business days for standard shipping. To Alaska, Hawaii, U.S. protectorate, P.O. box, and APO/FPO addresses allow 4-28 business days for Standard shipping. No expedited shipping. All orders placed with expedited shipping will be cancelled. Over 3, 000, 000 happy customers.
