166 FOUNDERS OF OCEANOGRAPHY 



knowledge of the variations in alkalinity throughout the year 

 has been increased greatly of late years by the work of the 

 Scandinavians, Palitzsch, Witting, and Sorensen, of the late 

 A. G. Mayer at the Carnegie Institute in the United States, 

 and of the late Benjamin Moore and others working in the 

 Irish Sea. The sea around the Isle of Man was noticed more 

 than ten years ago (in the course of our plankton work at 

 Port Erin) to be a good deal more alkaline in spring (say 

 April) than it is in summer (say July) ; and consequently, 

 during the years 1912 to 1914, Professor B. Moore and his 

 assistants undertook a detailed investigation at the Port Erin 

 Biological Station, and by examining samples of the sea- 

 water periodically, were able to show that there were marked 

 variations in the hydrogen-ion concentration, as indicated 

 by the relative degree of alkalinity, which gets low in summer 

 increases somewhat in autumn, and then decreases rapidly to 

 disappear practically during the winter ; and then, after 

 several months of a minimum, begins to come into evidence 

 again in March, and rapidly rises to its maximum in April or 

 May. This periodic change in alkalinity is seen to correspond 

 roughly with the changes in the living microscopic contents 

 of the sea represented by the phyto -plankton annual curve, 

 and the connection between the two phenomena is seen 

 when we realize that these changes in the alkalinity of the 

 water are due to the relative absence of carbon dioxide. In 

 early spring the rapidly developing myriads of Diatoms in 

 their metabolic processes use up the store of carbon dioxide 

 accumulated during the winter, or derived from the bi- 

 carbonates of calcium and magnesium, and so increase the 

 alkalinity of the water, until the maximum of alkalinity, 

 due to the fixation of the carbon and the reduction in the 

 amount of carbon dioxide present, corresponds with the crest 

 of the phyto -plankton curve in, say, April or May. 



Testing the alkalinity of the sea- water may therefore be 

 said to be merely ascertaining and measuring the results of 

 the photosynthetic activity of the great phyto -plankton rise 

 in spring due probably to the daily increase of sunlight. 



