SEA-FISHERIES LABORATORY. 233 



[Percy Sladen Memorial Trust Research.] 



STUDIES OF CERTAIN PHOTO-SYNTHETIC 

 PHENOMENA IN SEA-WATER. 



I.— SEASONAL VARIATIONS IN THE REACTION OF 

 SEA- WATER IN RELATION TO THE ACTIVITIES 

 OF VEGETABLE AND ANIMAL PLANKTON. 



II.— THE LIMITATIONS OF PHOTO-SYNTHESIS BY 

 ALGAE IN SEA-WATER. 



By Benjamin Moore, Edmund Brydges Rudhall Prideaux, 



and George Andrew Herdman. 



(From the Marine Biological Station, Port Erin, Isle of Man, 



and the Laboratories of Bio-Chemistry and Physical Chemistry, 



University of Liverpool.) 



Our attention was first drawn to the seasonal variations 

 in the alkalinity of sea-water recorded in this paper, and to 

 the remarkable degree to which green algae can reduce the 

 hydrogen-ion concentration of sea-water in which they are 

 grown, by preliminary observations made by Moore, Edie and 

 Whitley at Port Erin in the Spring of 1912. 



A severe epidemic of a disease, characterised by large 

 areas or rounded spots of ulceration on the skin, had killed a 

 considerable number of the plaice used for spawning purposes in 

 the pond attached to the Fish Hatchery, although this pond 

 had an abundant daily supply of fresh sea-water. 



At the request of Professor Herdman the water of the 

 pond was examined chemically, and the only important fact 

 discovered was that it was much more alkaline than the water 

 of the Bay. At the same time the pond- water was green in 

 colour from the presence of floating mono- cellular algae, and 

 a minute green flagellate Infusorian in great profusion, while, 



