68 THE SALTON SEA. 



Inspection of this table shows the extraordinary composition, as to both quality and 

 quantity, of the medium in whicli these brine organisms Uve. How any sort of balance, 

 osmotic, adsorptive, and chemical, is maintained against such odds, is difficult to understand. 



SUMMARY AND CONCLUSIONS. 



The favorable climatic conditions and the flat clayey parts of the shore of the Bay 

 of San Francisco are taken advantage of to manufacture salt from sea-water on a com- 

 mercial scale. Water is pumped from the Bay into shallow diked ponds. Containing 

 about 3 per cent common salt at this stage, it is concentrated by the sun's heat, the water 

 evaporating rapidly into the dry air of the rainless summer. In the course of this con- 

 centration, much of the calcium comes down, crystallizing out in the so-called "pickle 

 ponds." From these ponds the brine is again pumped into the salterns, where it under- 

 goes still further concentration by evaporation hastened by the sun's action. At the time 

 salt crystallizes out the percentage of common salt has reached nearly 30 per cent. Be- 

 sides being a satiu-ated solution of sodium chloride, such a brine is also a concentrated 

 solution of magnesium salts and contains a considerable proportion of potassium. Between 

 the proportion of calcium and magnesium in concentrated brines and in the mother-liquor 

 there can be no "balance"; but since, in other respects than lack of "balance," these solu- 

 tions are fatal but inhabited, they throw no real light on the value of the idea of "balanced 

 solutions" and only continue, if they do not justify, natural skepticism regarding it. 



The color of these brines, and often of the salt obtained from them, is due to a small red 

 chromogenic bacillus, but the brines are inhabited by a considerable number of organisms, 

 animals as well as plants. In the concentrated brines and in the mother-liquor from which 

 salt has been taken by crystallization the living plants are unicellular, members of the Poly- 

 blepharidaceae, motile green or brown organisms belonging to the genera Dunaliella and 

 Pyramimonas, and bacteria, which are often present in great numbers. These bacteria bring 

 about the destruction of animal waste and of plant remains which would otherwise encum- 

 ber the salterns, thus serving the same purposes that the putrefactive and other destructive 

 bacteria of the land and of the sea accomplish. The bacteria of decay adapted to waters of 

 the usual concentrations are killed by concentrated brines. The decay which must and does 

 go on in high brines is accomplished, therefore, by entirely different bacteria. At least one 

 of these is chromogenic and sometimes appears as the agent which turns salt cod-fish red. 



The behavior of the brine organisms is closely related to the changes which take 

 place in the brines in the course of the days, the seasons, and the process of salt manu- 

 facture. The brine algae are markedly phototactic and their distribution in the brine is 

 determined in great part by light and the direction from which it comes. Light does not 

 seem to determine the direction in which they shall divide, but division seems to occur 

 oftener and to take place more rapidly in darkness than in the light. (See Peirce, pp. 49-71.) 



The main changes, apart from the daily cycle of darkness and hght, taking place in 

 these brines are in the temperatures and concentrations of the solutions. The changes 

 in temperature exercise no very evident influence on the behavior of the brine organisms, 

 but the changes in the proportion of water are reflected in the behavior of the brine algse. 

 Inspection of the tables, and of the graphs constructed from them, shows that the num- 

 bers of the brine algae are directly proportioned to the amount of water in the solution, 

 and that increase in the amount of water is followed by increase of the algae by division. 

 The numbers of algae in the brines, as shown by collections and examinations extending 

 over five years, though reported in these tables only from mid- August 1911 to mid-May 

 1912, rise and fall with the proportion of water as this fluctuates in consequence of rain, 

 dilution of concentrated brine by additions from the "pickle ponds," evaporation, and 

 harvesting of salt. 



