60 



THE SALTON SEA. 



Table 22. — Record of living contents of samples of brine taken from six salterns — Continued. 



Tank No. 6 — Continued. 



Certain features of these records merit comment. The table shows the temperature of 

 the air (column headed Tem. air) in degrees centigrade, of the brine (column headed Tem. 

 brine), the specific gravity (Sp.gr.) of the brine, the clearness or cloudiness (Sun) at the time 

 of collecting, the numbers of Dunaliella viridis (No. of D. viridis) as determined by counting 

 the number of organisms in the field of the same microscopic objective and eye-piece when 

 the material was brought into the laboratory; and similarly of D. salina (No. of D. salina). 

 Pains were taken to make the conditions of these counts as nearly as possible the same week 

 after week; and as the counts were repeated for different fields in the same drop of brine and 

 in other drops of brine, the record of some, few, many, and very many, is fair and reliable. 

 Dunaliella viridis occurs in two forms: a small, slender, and very actively motile one, like a 

 slender pear, designated in the tables as z., though Teodoresco calls them gametes; and a 

 larger, plumper, and less rapidly moving one, designated in the tables as v., but called 

 zoospores by Teodoresco. Both forms divide under the conditions recorded in the tables, 

 and this is also shown to be the case in the cultures to be described subsequently. Duna- 

 liella salina also has these two forms (and others), but does not exhibit them so constantly. 

 The record in the column headed "water" is of the color of the brine as seen in a test tube 

 in the laboratory. A color recorded in this column as pinkish would indicate that the brine 

 in the salterns was red. Under Pyramimonas is recorded the presence of this peculiar 

 organism, but as I did not succeed in getting this in pure culture on agar-agar, as I did the 

 others, I can say little more about it. The column headed " Salt " shows whether or not 

 salt was forming. Under " Remarks " the rainfall and other items are recorded which bear a 

 relation to our organisms. 



Inspection of these tables shows that, between the density of the brines and the num- 

 bers of individuals of these three species of unicellular alga?, there exists an intimate rela- 

 tion. How intimate this is is indicated by reducing these tabular records to graphs, and 

 also by cultures. In figure 2 we have the records of Saltern No. 1 in graphical form. 

 The lower continuous line represents specific gravities of the brines as they were determined 

 week by week from August 16, 1911 (vm, 16, '11), to May 2, 1912 (v, 2, '12), a specific 



