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Show 294 TilE ROT IS IN to the light; but in the case of timb~r th~re is a gain. in consoJidation, and that is the mam pomt. "' The way in which the parts of ~he oak~' come farther shows the importance of light to 1t at the very instant the plumule begins to m_ove. By that time the root has penetrated to a cons1derable depth, and is furnished with absorbent rootlets. The nourishment which these procure cannot be a~ted. on by the light in them, and the plumule, bem~ JUSt beginning to move, has no leaves, so that 1f the cotyledons are buried in the earth, t~e oak must be(J'in life with all the weakness of an etlolate~ plant; and if it begins without the carbon and astrm~ency that are necessary for good oak ti~ber, the hmber of it must be bad, how long s?ever 1t may stand, or what size soever it may attam. Future treatment may make it grow faster or_ slower; b?t no f~tur_e treatment can change the _charac~er w1th wh1ch It starts. If it starts good timber, It may ?e. stunted or deformed, but it will be durable ; . and If It starts bad timber, it may be showy, but It can never be goTodo.o rich and stimulating a sm· l may a1 s o I· ~J· U!e the timber, even though the acorn, rupture_cl as 1~ IS, be exposed to the light; and if the a~orn IS bune_d, and the soil too rich at the same time, they w1ll jointly injure the quality of the tree. . . Cultivators sometimes forget (and It IS ofte!l_an unfortunate forgetfulness) that the h~althy cm~d1t10n of a plant does not depend on the sml, the mmsture, or the heat; that it does not depend upon all three jointly, or on the proportions that they_bear to each other. To that part of the pl3:nt wh1ch naturally lives in the air there must be light; and although their artificial heat without light may_ ~o for those roots that are naturally under ground, It IS extremely doubtful whether any substitute can be. fo"';lnd for the beams of the sun. So, if there is arti?cial heat applied to the leaves, its action will be 1m:perfect, THE NURSERY. 295 and the quality of the plant deteriorated, if there is not the light of the sun along with it. The soil, the humidity, the air, the heat, and the light must, like all causes which work jointly in producing an effect, be duly proportioned to each other; and when, in any combination of that kind there is any one of the causes over which we hav~ no control, we must regulate our measure of all the others by that. Now the light and heat of the sun are. the onl~ causes of the growth of vegetables wh1ch ar~ wit)lout the control of man as to quantity, and the light IS most exclusively so. We have not the_ smallest !?ower .over it, either in respect of duratiOn or of mtensity. Perhaps somethin(J' might be done by means of mirrors, but they h~ve not been tried, and they could not be used on the great ~cale. Indee~, it i~ probal;>le that any attempts to mcrease the mtens1ty of light by artificial means would do mischief rather than good. On sunny daY:s, any additional concentration· up, even to that wh~ch would burn t~e plants if dry, and boil them if mmst, could be obtamed; but then, as there is no calculating when it shall be sunshine and when cloudy, the transition from the artificially increased sunbeams to the natural shadow of clouds would be destructive. Thus the safe plan is to regulate all the other m~tters by the natural light. Here a little fact presents itself, which is not wholly unworthy of notice. The first necessary that man has to find, by skill and artificial means is food ; and light, the agent in vegetation ove; which he h~s the sm_allest control, appears to have less to. do m preparmg vegetables for food than in preparmg the~ for any other purpose. Succulent, · pulpy, and farmaceous matter, the kinds which are ~ost ~utritive, are b.est when prepared out of the 1mmed1ate reach of hght. When part of a potato is above_ the surface, the light turns it green, and the taste IS unpleasant. Allow it to be formed, and to |
