. Science-gossip . SCIENCE-GOSSIP. VARIATIONS OF THE LEAF-BLADE. Bv H. E. Griset. npO the botanist the important subject of thevariation of the lamina, and the cause ofthis variation, will ever possess the highestinterest, from its value in the determination ofplants; and there is little doubt that warmth andmoisture in the case of terrestrial plants favourthe growth of the parenchymatous and vasculartissues, as Mr. J. A. Wheldon remarks in his notesin the October number, upon the article of theabove heading. What can be the use of the dense one whole season; it will generally be found thatthe
. Science-gossip . SCIENCE-GOSSIP. VARIATIONS OF THE LEAF-BLADE. Bv H. E. Griset. npO the botanist the important subject of thevariation of the lamina, and the cause ofthis variation, will ever possess the highestinterest, from its value in the determination ofplants; and there is little doubt that warmth andmoisture in the case of terrestrial plants favourthe growth of the parenchymatous and vasculartissues, as Mr. J. A. Wheldon remarks in his notesin the October number, upon the article of theabove heading. What can be the use of the dense one whole season; it will generally be found thatthe leaves become larger as the warm weatheradvances. Thus on a single shoot about nineinches long, on May ist, a leaf was mature, itwas simply three-lobed, the casta of the medianlobe being lo centimetres long (lo centimetres, orI decimetre = 3937o8 inches), (fig. ij (-). OnJune 2nd, four more leaves had been formed,the fifth being deeply five-lobed with a mediancostal length of 15 centimetres (fig. 2) ; and on R^ 1. Variations of the 1-4, leaves of the fig-tree, Ficus carica ; figs. 5, 6, leaves cf the great bindweed. Convolvulus sepiiim. epidermis and mostly entire or solid form of theleaves of many succulent plants ? Is it not toprotect the more delicate parenchyma, w-hich inmembranous and divided leaves would obviously berapidly deprived of moisture in the dry atmosphereof the habitats of these plants ? In studying the forms of the leaves of the samespecies we are generally led to the conclusion thatthe largest and most divided leaves are produced inthe most favourable time of the year, which, ofcourse, varies with the species. This is well illus-trated : if the minute differences in the leaves ofthe fig-tree (i) (Ficus carica) are carefully noted for() This tree, which grew on a garden wall facing the west, June -iSth, three more leaves were matured, theeighth being seven-lobed, with a median costa of168 centimetres (fig. 3). Of course the other leavesformed
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