Corresponding estimates based upon the tree growth and in part also upon minor vegetation, are current in the richer lands also. The “black-oak and hickory uplands,” the “post-oak flats,” “hickory bottoms,” “gum bottoms,” “hackberry hammocks,” “post-oak prairie,” “red-cedar prairie,” and scores of other similar designations, possess a very definite meaning in the minds of farmers and are constantly used as a trustworthy basis for bargain and sale, and for crop estimates. Moreover, experienced men will even after many years’ cultivation be able to distinguish these various kinds of lands from one another. _Cogency of Conclusions based upon Native Growth._—Since the native vegetation normally represents the results of secular or even millennial adaptation of plants to climatic and soil-conditions, this use of the native flora seems eminently rational. Moreover, it is obvious that if we were able to interpret correctly the meaning of such vegetation with respect not only to cultural conditions and crops, but also as regards the exact physical and chemical nature of the soil, so as to recognize the _causes_ of the observed vegetative preferences; we should be enabled to project that recognition into those cases where native vegetation is not present to serve as a guide; and we might thus render the physical and chemical examination of soils as useful practically, _everywhere_, as is, locally, the observation of the native growths. To a certain extent, such knowledge would be useful in determining the salient characters of cultivated soils, also; and would be the more useful and definite in its practical indications the more nearly the cultural history of the land is known, and the less the latter has been changed by fertilization. For, so soon as the first flush of production has passed, the question of how to fertilize most effectually and cheaply demands solution. It was from this standpoint, suggested by his early experience in the Middle West and subsequently most impressively presented to him in the prosecution of the geological and agricultural survey of Mississippi, that the writer originally undertook, in 1857, the detailed study of the physical characters and chemical composition of soils. It seemed to him incredible that the well-defined and practically so important distinctions based on natural vegetation, everywhere recognized and continually acted upon by farmers and settlers, should not be traceable to definite physical and chemical differences in the respective lands, by competent, comprehensively-trained scientific observers, whose field of vision should be broad enough to embrace concurrently the several points of view—geological, physical, chemical and botanical—that must be conjointly considered in forming one’s judgment of land. Such trained observers should not merely do as well as the “untutored farmer,” but a great deal better.