THE BEHAVIOR OF CERTAIN MICRO-ORGANISMS IN BRINE. 



61 



gravity of 1.245 on October 11, 1911, being the highest encountered, and of 1.0175 on Decem- 

 ber 29, 1911, the lowest during this period. Immediately above this line indicating the 

 specific gravities is a broken line showing the numbers of brown unicellular alga; belong- 

 ing to the species Dunaliella salina. Comparison of the course of these two lines will show 

 that, in the main, there is a remarkable similarity; with the increase in water in the brine 



Fia. 2. — Diagram showing fluctuations of water and of organisms in brine. 



Continuous line: varying specific gravity of brine under the influence of showers and of continued rain. 



Broken line ( ) indicates numbers of Dunaliella salina varying with the dilution of the brine (note the increase 



in numbers with every increase in water). 

 Continuous line connecting circles: indicates numbers of Pyramimonas sp.? varying only with the principal 



fluctuations in water-content of the brine. 

 Broken line connecting circles indicates numbers of Dunaliella viridis varying with the dilution of the brine (note 



the mortality when water suddenly increased). 

 Observations made at weekly intervale, as indicated by horizontal line at the bottom. 



there is an increase in the number of individuals of this characteristically brine alga. 

 Thus on September 2S, following a decided decrease in the concentration of the brine 

 (from sp. gr. 1.2425 to 1.225), owing to the addition of brine from a "pickle-pond," there 



