SEA-FISHERIES LABORATORY. 71 



police boat. They were sorted out into sexes, and the degree 

 of maturity was observed in each shrimp. The spawning 

 period is principally in the spring months, but some shrimps 

 carrying eggs can be found at any time throughout the year. 



Work at Sea, at Port Erin, and elsewhere. 



Hydrographic Observations. 



Dr. Bassett reports as usual on the observations and 

 analyses of samples of water made during the first portion 

 of the year, including September ; but does not attempt to 

 draw conclusions from his data, on account of the record being 

 incomplete this year. 

 Plankton Investigations. 



With the expert help of Mr. Scott and Miss H. M. Lewis, 

 I have continued the " Intensive Study " of the samples of 

 plankton taken off Port Erin (as a central point in the Irish Sea) 

 throughout the year. We report upon our results as usual, 

 but these are of a detailed nature and do not call for any 

 general comment. 



Photosynthesis and the Alkalinity of Sea-water. 



Professor B. Moore and his two fellow- workers have given 



us an interesting series of studies of photosynthetic phenomena 



in sea-water, as the result of observations and experiments 



made at Port Erin at various times between August, 1912 and 



January, 1915. They discuss (1) the extent and nature of 



the seasonal variations in the alkalinity of the sea, and (2) the 



limits of photosynthesis by algse as the alkalinity due to their 



action increases, and show that the increase in the alkalinity 



of the sea in spring is not due to increasing temperature 



disturbing the equilibrium between the carbon-dioxide of the 



sea and the atmosphere, but is caused by the photosynthesis of 



the innumerable minute plants (Diatoms) present at that time 



in the water. w A HERDMAN. 



Fisheries Laboratory, 



University of Liverpool, 

 March 24th, 1915. 



