Meadows hold out without Change of Species of Grass, tho’ a Crop be carried off every Year; the Richness of that Soil, with the Help of the Atmosphere, Dung of Cattle in feeding the After-Crop, or else Flooding, from the overflowing of some River, some, or all of which, supply the Place of the Plough to a Meadow. Woods also hold out beyond Memory or Tradition, without changing Sorts of Trees; and this by the Leaves, and perhaps old Wood, rotting on the Soil annually, which operate as a Manure; because, as has been said, Earth which has once passed any Vessels, is so changed, that, for a long time after, it does not retain its Homogeneity[214] so much as to mix with pure Earth, without fermenting; and by the Descent of the Atmosphere, the Trees shadowing the Soil, to prevent the Re-ascent of what that brings down; all this, resembling Tillage, continually divides the Soil, and renews the Food equal to the Consumption of it made by the Wood. [214] Not that the Particles of Earth are strictly homogeneous, but that they are much less heterogeneous, before they are altered by Vessels, than afterwards. And the last Argument I shall attempt to bring for Confirmation of all I have advanced, is that which proves both the Truth and Use of the rest; _viz._ That when any Sort of Vegetable, by the due Degrees of Heat and Moisture it requires, is agreeable to a Soil, it may, by the new Horse-hoeing Husbandry, be continued without ever changing the Species. 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. 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[215], or upper Stratum, wherein the Plough is exercised. [215] This hollow Matter lets the Water pass down the sooner from the Surface, whereby the Staple or the Ground becomes the drier, and consequently warmer.