234 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



as usual at this time of year, the sea- water in the Bay was 

 almost free from green organisms. It was also observed that 

 the water of the Bay was less alkaline to phenol-phthalein than 

 it had been on previous occasions when titrated in connection 

 with other work. 



For these reasons, it was determined to follow up the 

 reaction of the sea- water at intervals throughout the round of 

 the year, and also to make a series of observations as to the 

 speed with which green organisms added to a confined volume 

 of sea-water increased the alkalinity, and the limit to which 

 the alkalinity could be so raised before photo-synthetic action 

 ceased, or the organism perished. 



I. — Seasonal Variations in the Alkalinity of Sea- Water. 



Certain of the observations were carried out by Moore, 

 Edie, and Whitley in August, 1912 ; the remainder were made 

 by the present authors since that time. 



Three types of observation were carried out : — 



1. Titrations were made of a measured volume of sea- 

 water to two coloured indicators, viz., phenol-phthalein and 

 methyl- orange using centi-normal solutions of hydrochloric 

 acid. These titrations give the required amount of alkali to 

 alter the hydrogen-ion concentration from approximately 

 P H; 10~ 8 to P H , 10~ 4,5 and indicate quantitatively what has been 

 termed qualitatively by Sorensen 2 the " Buffer " effect of the 

 dissolved alkali-acid, or amphoteric, salts, and by Moore and 

 Wilson 5 the " Reactivity " of the solution due to these same 

 amphoteric solutes. This determination is one of great 

 importance in estimating the characteristics of a physiological 

 solution, since upon it depends the protective action against 

 large variations in hydrogen-ion concentration. 



2. The hydrogen-ion concentration was determined by 

 the colorimetric method introduced by Friedenthal and Salm 1 

 and amplified and improved by Sorensen 2 ' 3 and Palitzsch. 4 



