. Elementary botany. Botany. 378 RELATION TO ENVIRONMENT. 739. Function of the bud-coverings.—It is popularly be- lieved that the scales and liairy coverings serve to keep the bud warm. Research, however, shows this to be almost entirely erroneous, and that the thin bud coverings are en- tirely inadequate to keep out the cold of winter. They cannot keep the bud even a degree or two warmer than HA the outside air, except when the changes are very rapid. Experiment also shows that the modifying effect of the covering when the bud thaws out is so shght as to be almost neg- ligil)le. Indeed, a the
. Elementary botany. Botany. 378 RELATION TO ENVIRONMENT. 739. Function of the bud-coverings.—It is popularly be- lieved that the scales and liairy coverings serve to keep the bud warm. Research, however, shows this to be almost entirely erroneous, and that the thin bud coverings are en- tirely inadequate to keep out the cold of winter. They cannot keep the bud even a degree or two warmer than HA the outside air, except when the changes are very rapid. Experiment also shows that the modifying effect of the covering when the bud thaws out is so shght as to be almost neg- ligil)le. Indeed, a thermometer bulb covered with scales taken from a horse-chestnut Inid warmed up more rapidl}' than a naked one when ex- posed to sunshine. Tlie wool in the liorse-chestnut bud is not for the pur- pose of keeping it warm, but to pro- tect tlie voung shoot from too great trans])iration after the bud opens the following spring. Research has also Bud of European elm in sec- sliowu thai sucli tempering of the ti'Hi, 5nr)\vui>^ iiverlappinR ol ^ s^^i'^s- heat conditions is not especiallv bene- ficial to the plant, as was once thouglit. Xcitlicr can we find the main function in tlie prevention of water from entering tlie Inid. This might l)e accomplished in much sim])ler ways, e\'cn if we could demonstrate the desiraliilit\' of kee]:)ing the water out at all. The true functions of tlie l)U(l-scales are two in mmilicr: Firstlv, llic prc\"cntirin of too great loss of water from the voung and delivalc (larts witliin; and sccondl\-, tlie protection of these same jiarls from mecliaiii(al inillr^•. \\'illioul sonic such jiro- tcction the delicate "\'oiing siruc lures would be l)eaten off b\' the wind, or beionie the food 'or lninu;ry liirds during the long win- ter Fir. 430. 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 rese
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