The natural history of plants, their forms, growth, reproduction, and distribution; . puckering ,- of the margin of the leaf is attended in the water-lilies by a phenomenon which, although not directly asso-ciated with the matter in hand, is so full of interest that it cannot be passed without notice. If we take a boat in the bright sunshine at mid-day, and float over the calm inlet of a lake, whose surface is overspread with the leaves of water-lilies, and if the water is clear to the bottom, we shall see the sha-dows of the leaves which float on the surface sketched out on the ground
The natural history of plants, their forms, growth, reproduction, and distribution; . puckering ,- of the margin of the leaf is attended in the water-lilies by a phenomenon which, although not directly asso-ciated with the matter in hand, is so full of interest that it cannot be passed without notice. If we take a boat in the bright sunshine at mid-day, and float over the calm inlet of a lake, whose surface is overspread with the leaves of water-lilies, and if the water is clear to the bottom, we shall see the sha-dows of the leaves which float on the surface sketched out on the ground below. But we can scarcely believe our eyes—these do not look like the! shadows of theI leaves of water-I lilies, but ratherI of the fronds of huge fan-palms. From a dark central portion raaiate out long dark strips which are separated from each other by as many light bands. The cause of this peculiar form of shadow is to be found in the undulating margin of the floating leaves. The water of the lake adheres to the whole of the under surface of the arched portions 19 Fig. disc as far as the edge, and is drawn up by capillarity to Vol. I. the 290 MAINTENANCE OF A FREE PASSAGE FOR AQUEOUS VAPOUR. of the undulating margin. The suns rays are refracted as through a lens by thisraised water, and so a light stripe corresponding to each convex division of thecurved margin is formed on the bed of the lake, and a dark stripe corresponding toeach concave part. These are arranged in a radiating manner round the darkcentral portion of the shadow. MAINTENANCE OF A FEEE PASSAGE FOR AQUEOUS VAPOUR. Special arrangements are met with in all plants which possess stomata, in orderthat the giving off of aqueous vapour may continue without hindrance. Waterfalling on the upper side of the leaf, in the form of rain and dew, threatens tocause the greatest obstacle to this free passage should it be able to collect directlyin the stomata. The width of an open stomate does not render the entranc
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1902
