analytical tests before we may hope to reach any conclusions that may be concisely expressed or widely applied.
The results obtained by the studies which have just been brought to a stage of completion of the Salton Sea furnish us with some very suggestive facts as to the influence of the substratum upon organisms. The waters of this sea when it stood at maximum level in 1907 contained about one fourth of one per cent, of dissolved material, principally salts of sodium, potassium and magnesium. The recession of the lake by evaporation left bare a new strip of strand each year, which was saturated with a solution differing from that of the preceding year by about one fifth of one per cent, in concentration with some changes in relative value of the various substances, especially the calcium and magnesium. Accompanying such conditions, an Aster, a Prosopis, a Scirpus and an Atriplex have shown variations not hitherto seen in these species. Especial interest attaches to these occurrences from the fact that there are seven species endemic below the level which the ancient body of water, Blake Sea, must have reached three or four centuries ago. In other words, these seven species are found nowhere but on the beaches of the lake and there is a strong presumption that this restricted occurrence is due to their origination in the place and that they have not spread beyond the ancient sea-bed.
The facts brought out in the foregoing discussion are presented not so much to denote actual progress in our researches as to illustrate the character of some of the problems under consideration. The inquiry as to the integrity of purpose and validity of results of such work is a question which may rightly be directed toward every project which absorbs funds and consumes the time and energy of the investigator and the worker. Something of the wider purposes and fundamental character of the problems attacked are suggested by the results and plans which have been discussed. In addition it seems necessary to say to those who mistakenly attribute a directly economic purpose to the Desert Laboratory that none of its facilities are devoted to agricultural experimentation. This is a function especially pertaining to the government, and so far as our own is concerned a function that is most efficiently carried out. It is clear, however, that the data being accumulated at the Desert Laboratory may in time constitute an important contribution to the physical and biological principles to be considered in the occupation and utilization of arid regions. When it is taken into account that the world-wide progress of civilization with its attendant extended occupancy of the surface of the earth has brought the race to a point where it must consider seriously methods for the more intensive use of the areas already occupied, and also bring into usefulness the arid areas which comprise one fifth of the total land area, the importance of this possibility may be realized.
