This principle is of considerable practical importance, especially in the eastern third of the United States. Generally speaking, clay and silt soils have a greater natural fertility than sandy soils; limestone soils than those that are deficient in lime. Thus soils that naturally grow chestnut trees, indicating a low lime content, have a tendency to deteriorate under exhaustive cropping much more rapidly than limestone soils. More fertilizers and other methods of soil improvement are necessary in the case of chestnut soils than in the case of limestone valley soils. One of the first questions to ask, therefore, concerning an unknown farm in Pennsylvania is whether or not chestnut trees grow naturally. It does not follow, however, that chestnut soils are undesirable. Much will depend upon the crop or crops it is desired to raise. For example, in some regions they are well adapted to potatoes and peaches. In these cases the cost of the fertilizers necessary to keep the soil in proper condition is small compared with the total return from the crop. The pioneer's best guide as to the value of new land was and is the vegetation growing upon it, and, especially in a wooded country, the native trees. Basswood, crab apple, wild plum, black walnut, ash, hickory and hard maple generally indicate a fertile soil. White oak indicates only a moderate soil; bur oak, a somewhat warmer and better drained soil. Beech indicates a rather poor soil; a heavy clay, lacking in organic matter. Certain species of elms, maples and oaks, as red maple and the Spanish swamp oak, indicate wet soils. The occurrence and vigor of certain herbaceous plants are especially indicative of fertility of the soil, as, for example, ragweed, bindweed, certain plants of the sunflower family, such as goldenrod, asters and wild sunflowers. Soils adapted to red clover and alfalfa are usually well drained and contain plenty of lime. Alsike clover will grow on a soil too wet or containing too little lime for either of the former. Soils that produce sorrel and redtop when red clover and timothy are sown need drainage or liming or both. Sedges usually indicate a wet soil, although certain species grow on dry, sandy soils. The point of this paragraph, however, is not to give comprehensive advice but to cause the young farmer to observe the conditions and make his own applications, which will vary in different regions and under different circumstances. Perhaps the one feature that the young farmer is most likely to overlook in the selection of a farm is the relative proportion of tillable land. One farm of 200 acres, may, on account of stony land, wet land, comparatively unproductive woodland, or because of the arrangement of fences and roadways, contain only eighty acres of tillable land, while another may contain 160 acres. This is one reason why a 160-acre farm in the central West may be more valuable than a farm of the same size in the northeastern United States.