ENVIRONIC FACTORS 433 



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 sug- 

 gestive 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 satu- 

 rated 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. Espe- 

 cial 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 be- 

 yond 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 ques- 

 tion 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 Labora- 

 tory that none of its facilities are devoted to agricultural experimenta- 

 tion. 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 occu- 

 pancy 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. 



vol. lxxxiv. — 30. 



