Horse-Hoeing Husbandry 238-241 (1751)
Jethro Tull

Chap. XV

Of Change of INDIVIDUALS

SEEDS, in their natural Climate, do not degenerate, unless Culture has improved them; and then, upon Omission of that Culture, they return to their first natural State.

(a)This hollow Matter lets the Water pass down the sooner from the Surface, whereby the Staple of the Ground becomes the drier, and consequently warmer.

As the Benefit of changing of Species of Seeds is from Difference of Tillage, so the Benefit of changing Individuals of the same Species appears to be from those Causes which are, generally, themselves, the Effects of different Climates, such as Heat and Moisture, which may also vary very much in the same Latitude and Neighbourhood; as the same Mountain, in the Country of the Mogul (related by Mr. Evelyn, from Monsieur Bernier), on the South Side produces Indian Plants, and on the North Side European Plants, from different Exposures; and some Land, retaining Water longer, is colder; some, suffering it to pass down quicker, and by the Nature and Figure of its Parts, causes such a Refraction and Reflexion of the Sun's Rays, which give a great Warmth, as in Sand, and gravelly Grounds, that are well situate, and have an under Stratum of some Sort of hollow Matter, next under the Staple (a), or upper Stratum, wherein the Plough is exercised.

This beneficial Change of Individuals seems rather to be from the forementioned Causes, than from Change of Food; and these Causes shew their Efficacy, chiefly in the Generation or Foetation of those Seeds; as Flax-seed brought from Holland, and sown here, will bring as fine Flax as there; but the very next Generation of it coarser, and so degenerating gradually, after Two or Three Descents, becomes no better than the common ordinary Sort; yet its Food is the same, when the Flax is fine, as when 'tis coarse.

And so it is, when Individuals of Wheat are changed: So Silkworms, hatch'd and bred in France, of Eggs or Seed brought from Italy, will make as fine Silk as the Italian; but the Eggs of these laid in France, and their Issue, will make no better Silk than the French; though their Food be from Leaves of the same Mulberry-trees, when they make fine Silk and coarse: Therefore 'tis from the Climate, where the Eggs are impregnated, not where they have their Incubation or Food when hatch'd, and fed to their Lives End, that this Difference happens.

(b) Barley is far from being improved by becoming rath-ripe; for it loses more good Qualities than it gets by being sown at Patney: 'Tis so tender, that if it be sown early, the Frost is apt to kill it; or if it be sown late in May, on the same Day, and in the same Soil, with the same Sort of Barley that is not rath-ripe, it will be much thinner bodied than the late-ripe; and besides, if it happens to have any Check by Cold or Drought, it never recovers it as the other doth, at what time soever it is sown. It is now, I am informed, gone out of Fashion, and very few Farmers have sown it of late Years. I know a little Parish, that, I believe, formerly lost about Two hundred Pounds per Ann. by sowing rath-ripe Barley: But long and dear Experience hath now convinced them of their Error, and obliged them totally to disuse it.

Common Barley, sown once in the burning Sand, at Patney in Wiltshire, will, for many Years after, if sown on indifferent warm Ground, be ripe Two or Three Weeks sooner than any other (b), which has never been impregnate at Patney: But if sown a Degree farther North, on cold clayey Land, will, in Two or Three Years, lose this Quality, and become as late-ripe as any other.

Indeed Patney is far from improving the Species of Barley, except we think it improved by becoming more weak and tender, and shorter-lived; which last-mentioned Quality fits it for such Countries, where the Summers are too short for other Barley to ripen.

The Grains or Seeds of Vegetables are their Eggs; and the individual Plants, immediately proceeding from them, have not only the Virtues they received in Embryo (or rather in plantulis), but the Diseases also; for when smutty Wheat is sown, unless the Year prove very favourable, the Crop will be smutty; which is an evident Token of mala stamina.

The smutty Grains will not grow; for they turn to a black Powder: But when some of these are in a Crop, then, to be sure, many of the rest are infected; and the Disease will shew itself in the next Generation, or Descent of it, if the Year wherein 'tis planted, prove a wet one.

Weeds, and their Seed, in the Fields where they grow naturally, for Time immemorial, come to as great Perfection as ever, without Change of Soil.

These Weeds, with Acorns, and other Masts, Crabs, Sloes, Hips, and Haws, are thought to have been, originally, the only natural Product of our Climate: Therefore other Plants being Exotics, many of them, as to their Individuals, require Culture and Change of Soil, without which they are liable, more or less, to degenerate.

But to say, that the Soil can cause Wheat to degenerate into Rye, or convert Rye into Wheat, is what reflects upon the Credit of Laurembergius; 'Tis as easy to believe, that an Horse, by feeding in a certain Pasture, will degenerate into a Bull, and in other Pasture revert to an Horse again; these are scarce of more different Species than Wheat and Rye are: If the different Soil of Wittemberg and Touringia change one Species, they may the other.