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. 1886 Excerpt: ...open at the top, while those which are pendent do so at the base. F 66 SWIMMING SPORES. EYE-SPOT. chap. In other cases the dispersion is ...
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. 1886 Excerpt: ...open at the top, while those which are pendent do so at the base. F 66 SWIMMING SPORES. EYE-SPOT. chap. In other cases the dispersion is mainly the work of the seed itself. In some of the lower plants, as, for instance, in many seaweeds, and in some allied freshwater plants, such as Vaucheria, the spores1 are covered by vibratile cilia, and actually swim about in the water, like infusoria, till they have found a suitable spot on which to grow. Nay, so much do the spores of some seaweeds resemble animals, that they are provided with a red "eye-spot" as it has been called, which, at any rate, seems so far to deserve the name that it appears to be sensitive to light. This mode of progression is, however, only suitable to water plants. One group of small, loworganised plants, Marchantia, develop among the spores a number of cells with spirally thickened walls, which, by their contractility, are supposed to disseminate the spores. In the common Horsetails Equisetuni), again, the spores are provided with curious filaments, terminating in expansions, and known as "elaters." These move with great vigour, and probably serve the same purpose. In much more numerous cases, seeds are carried by the wind. For this of course it is desirable that they should be light. Sometimes this object is attained by the character of the tissues themselves, sometimes by the presence of empty spaces. Thus, in Valerianella auricula, the fruit contains three cells, each of which would naturally be expected to contain a seed. One seed only, however, is developed, but, as may be seen from the figure given in Mr. Bentham's excellent III. SEED CARRIED BY WIND. 67 1 I need hardly observe that, botanically, these are not tme feeds, but rather motile buds. Handbook of the Bri...
Half Lthr. st Edn. Illus. xv, 147 pp. Covers and backstrip shewing wear; library label verso f. cover; hinges strained; stamp prelims and plates; ink numbers on title page; some dust marking and; browning. Pencil marking in text.
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