262 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Experiment 4. This experiment was made to test the 

 rapidity of action in an early summer period and was not 

 carried to the end as the others. June 14th, 1913, at 10 a.m., 

 seaweed placed in water, about 2,000 c.c, in fully-stoppered 

 bottle. Titration value of water, at commencement, 3-7 c.c. 

 alkaline. Again titrated at 10 a.m. next day, after bright 

 sunshine meanwhile, titration had increased to 8-7 alkaline. 

 Sorensen had gone up from 6-1 : 3-9, Borate and Hydrochloric 

 acid to 9-4 : 0-6, equivalent to P H , 10" 9 - . 



Summary and Conclusions. 



1. Photo-synthesis by green algae causes a marked 

 diminution in hydrogen-ion concentration in sea-water, and 

 in confined volumes of water this variation in the direction of 

 increased alkalinity may act as the inducing or favouring 

 cause for pathological conditions and disease. 



2. Certain salts of the sea- water (notably carbonate and 

 bi-carbonate of magnesium) act as a steadying agency in 

 preventing too rapid variations in the ionic concentrations of 

 hydrogen and hydroxyl, and so safeguard life in the ocean. 

 Within viable limits, physiological activity may be stimulated 

 at certain seasons in which the alkalinity of the sea-water is 

 increased, or, in other words its hydrogen-ion concentration 

 diminished. Thus a rise in alkalinity in Spring would aid, 

 along with temperature and sunlight, in producing increased 

 cell-division. 



3. The " Buffer " effect or " Reactivity " of sea- water 

 has been estimated between two fixed points, viz., the turning 

 point to methyl- orange and the turning point to phenol- 

 phthalein, and found to correspond to about 22 x 10~ 4 N. 

 This range of " Reactivity " does not show seasonal variation, 

 and the hydrogen and hydroxyl ionic concentrations simply 

 vary within its limits. 



