salts it may have taken into solution during its sojourn beneath the surface. These soluble salts are left at the surface by the final evaporation of the water, and, as the process is continuous until the reservoir beneath is exhausted, the salts accumulate. Contrast this now with the action going on in a moist country. Here the copious waters wash the soils as rapidly as the salts come up from below, and carry them in solution into the drainage channels. During the greater part of the year the movement of the waters is partly from the surface downward into the subterranean water courses, from which they emerge in springs; partly by surface drainages into rills, and thence into living streams. By both movements, any tendency to accumulate soluble salts at the surface during the relatively brief periods of dryness is prevented. In a dry country the periods of dryness are very much longer, and the rainfall is seldom sufficient to wash the accumulated salts from the soil. There is, however, usually a limit to this accumulation, since at long intervals rains occur sufficient to remove a large portion of the salts. The difference between a dry and wet country in this respect is therefore one of degree rather than of kind. In a dry country the periods of accumulation of salts at the surface are long and continuous, while the washings of the soil are rare and imperfect. In a wet country the periods of accumulation are short and rare, while the washings are frequent, copious, and thorough.