A great Quantity also of the Sun’s Rays is necessary to keep Wheat strong, and in Health; and in Egypt, and other hot Countries, it is not so apt to fall, as it is when sown in Northern Climates, tho’ the Produce of the South be the greatest[152].
[152]This proves that the Crop doth not lodge on account of its Bigness.
It may be observ’d, that every Leaf is inserted into a Sort of Knot, which probably delivers the Sap to be depurated at the Vesiculæ of the Leaves, and then receives it back again for the Nourishment of the Plant, doing for that Purpose the Office of an Heart: But the Sun with his Rays supplies the Part of Pulse, to keep the Sap in Motion, and carry on its Circulation, instead of the Heart’s Systole and Diastole. Wheat, being doubtless originally a Native of a hot Country, requires by its Constitution a considerable Degree of Heat to bring it to Perfection; and if much of that Degree be wanting, the Wheat will be the weaker; and when the Solar Rays cannot reach the lower Parts of the Stalks, the lowest Leaves and Knots cannot do their Office; for which Reason the Chyle must mount higher before it be made into Sap, and there must be then a greater Mixture of crude Chyle next to the Ground, as by the white Colour it appears[153]. By this Means that Part, which, if it had a due Share of the Sun’s Influence, would be harden’d like a Bone or Spring, for the Support of the Stalks, for lack of that, becomes more like to a Cartilage, soft and weak, unable to sustain the Weight of the bending Ear, which, having its greatest Impetus against this Part, which is most feeble to resist it, it yields, and lets it fall to the Ground; and then the Grain will be blighted.
[153]But now I suspect this to be a Mistake, it being more likely, that the white Colour of the Rind is owing to the Absence of the Sun and free Air, than to the Chyle, as the Skin of those Parts of our own Bodies that are concealed from them, is whiter than of those which are exposed to them, though no Chyle-vessel comes near our Skin.
There is also another Cause of the Blight; and that is, the Wheat’s coming too late into Blossom. The usual Time is the Beginning of June; and if it be later, the Days shorten so fast after the Solstice, that the Autumn of the Year hastening the Autumn of the Wheat’s Life, the full Time of its Pregnancy[154] is not accomplish’d; and then its Fruit, which is the Grain, becomes as it were abortive, and not full-grown. This Time betwixt the Generation, Blossoming, and the Maturity of the Grain, is, or ought to be, about Two Months.
[154]Ut enim Mulieres habent ad Partum Dies certos, sic Arbores ac Fruges. Varro, Lib. 1. Cap. 44.
Mense Maio florent; sic Frumenta, & Ordeum, & quæ sunt Seminis singularis, Octo diebus florebunt, & deinde per Dies 40. grandescunt Flore deposito usque ad Maturitatis Eventum. Palladius, Pag. 114, 115.
Quindecim Diebus esse in Vaginis, Quindecim florere, Quindecim exarescere, cum sit maturum Frumentum. Varro, Lib. 1. Cap. 32.
But the different Heat that there is in different Climates, may alter both the Time that Plants continue in Blossom, and the Time betwixt the Blossoming and the Ripening.
Therefore ’tis advantageous to hasten, what we can, the Time of Blossoming, and to protract the Time of Ripening: And ’tis observ’d, that the earliest sown Wheat generally escapes the Blight the best, because it comes first into Blossom.