52 THE SALTON SEA. 



ness in San Jose (and also over the salt ponds near Redwood City) at mid-day in May, 

 June, July, August, and September is very small indeed, even less than at 8 p.m. Into 

 this clear air, therefore, with an average humidity of 54 per cent and an average tempera- 

 ture of 72.5° at 8 p.m., water will evaporate more and more rapidly as the temperature 

 rises; for, owing to the dryness of the ground, the humidity will fall very rapidly from 

 morning to mid-day, to rise again, but more slowly, from mid-day to night. 



In the climatic conditions, then, on the shores of San Francisco Bay the conditions 

 for rapid and great concentration of brines by natural means are very favorable. This 

 is plainly proved by the extensive scale on which salt is made from Bay water on these 

 shores, and it is precisely the climatic conditions which promote the manufacture of salt 

 from sea (Bay) water on a large commercial scale which influence the peculiar organisms 

 inhabiting concentrated brines. 



LITERATURE. 



Kellogg, 1 in a brief note describing a new species of peculiar crustaceans inhabiting 

 concentrating salt solutions, refers to various other papers on the animals of this peculiar 

 habitat. The plants of concentrated salt solutions have received comparatively little 

 attention. Hamburger 2 gives a bibliography to which need be added only a second paper 

 on the same subject by Teodoresco. 3 Oltmanns 4 makes scanty reference to the brine 

 alga? and points out the incompleteness of our information about them and their environ- 

 ment. 



What seems most commonly to have drawn attention to pools of brine, whether 

 natural or artificial, is the peculiar color of the water, red, of a shade between that of 

 fresh iron-rust and of blood. Miss Hamburger gives a historical sketch of the studies and 

 explanations of the color. These explanations were some of them chemical, some biological, 

 so contradictory in the early part of the last century that the Academie des Sciences 

 Naturelles, Paris, appointed first a commissioner and later a commission to determine 

 the facts. Apparently the first biological explanation was that the color was due to the 

 small animals (Artemia) found swimming in the water. Then the color was attributed 

 to unicellular algae variously called Protococcus saliniis (Dunal), Chlamydomonas dunalii 

 (Cohn), Dunaliella salina (Teodoresco), etc. And I wish to offer still another, namely, 

 the red chromogenic bacteria which grow in these concentrated brines and even in and 

 upon heaps of crude salt. 



The various explanations given from time to time by scientific men I have heard 

 advanced or reported by those connected with the salt works on the shores of San Fran- 

 cisco Bay. The simplest conjecture is that the color is due to iron. There may be iron in 

 the brine of some localities, but there is no considerable proportion in the brines which 

 I have studied most, as the analyses given later (p. 67) show, and since the color of brine 

 and salt is found to disappear permanently on heating, it is obvious that the color has 

 another cause. Screening out the Artemias does not remove the color, and one may find 

 colorless Artemias, for that matter, in colorless brines. So, too, one may find the above- 

 named algoo in great numbers in uncolored brines, or, on the other hand, fail to remove 

 the color of a red brine by filtering it. It must be admitted that filtration of concentrated 

 brines is very slow and imperfect, the filters clogging with suspended salt and organic 

 matter. But proof of the cause of the red color is furnished by inoculating a colorless and 

 sterile natural brine from a pure culture of the red chromogenic bacteria. The brine, and 



1 Kellogg, V. L. A new Artemia and its life conditions. Science, N. S., xxiv, 1906. 



2 Hamburger, Clara. Zur Kenntniss der Dunaliella salina und einer Amobe aus Salinenwasser von Cagliari. 



Archiv fur Protisten-Kunde, vi, 1905. 



3 Teodoresco, E. C. Observations morphologiques et biologiques sur le genre Dunaliella. Revue generate de 



Botanique, xvm, 1906. 



4 Oltmanns, F. Morphologie und Biologie der Algen. 2 Bande, 1904, 1905. 



