lands, but varieties especially adapted to the prevailing dry-farm conditions must be used if any certainty of harvest is desired.  Plants possess a marvelous power of adaptation to environment, and this power becomes stronger as successive generations of plants are grown under the given conditions.  Thus, plants which have been grown for long periods of time in countries of abundant rainfall and characteristic humid climate and soil yield well under such conditions, but usually suffer and die or at best yield scantily if planted in hot rainless countries with deep soils.  Yet, such plants, if grown year after year under arid conditions, become accustomed to warmth and dryness and in time will yield perhaps nearly as well or it may be better in their new surroundings.  The dry-farmer who looks for large harvests must use every care to secure varieties of crops that through generations of breeding have become adapted to the conditions prevailing on his farm.  Home-grown seeds, if grown properly, are therefore of the highest value.  In fact, in the districts where dry-farming has been practiced longest the best yielding varieties are, with very few exceptions, those that have been grown for many successive years on the same lands.  The comparative newness of the attempts to produce profitable crops in the present dry-farming territory and the consequent absence of home-grown seed has rendered it wise to explore other regions of the world, with similar climatic conditions, but long inhabited, for suitable crop varieties.  The United States Department of Agriculture has accomplished much good work in this direction.  The breeding of new varieties by scientific methods is also important, though really valuable results cannot be expected for many years to come.  When results do come from breeding experiments, they will probably be of the greatest value to the dry-farmer.  Meanwhile, it must be acknowledged that at the present, our knowledge of dry-farm crops is extremely limited.  Every year will probably bring new additions to the list and great improvements of the crops and varieties now recommended.  The progressive dry-farmer should therefore keep in close touch with state and government workers concerning the best varieties to use.

Moreover, while the various sections of the dry-farming territory are alike in receiving a small amount of rainfall, they are widely different in other conditions affecting plant growth, such as soils, winds, average temperature, and character and severity of the winters.  Until trials have been made in all these varying localities, it is not safe to make unqualified recommendations of any crop or crop variety.  At the present we can only say that for dry-farm purposes we must have plants that will produce the maximum quantity of dry matter with the minimum quantity of water; and that their periods of growth must be the shortest possible.  However, enough work has been done to establish some general rules for the guidance of the dry-farmer in the selection of crops.  Undoubtedly, we have as yet had only a glimpse of the vast crop possibilities of the dry-farming territory in the United States, as well as in other countries.