330 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



maximum was also in that month ; so that, in fact, as the 

 figures show, each of the two very different sunshine 

 curves is followed by a closely similar plankton curve. 

 With the view of testing whether there seemed to be 

 any correspondence between the sunshine day by day and 

 the plankton, especially the surface phyto-plankton, 

 exposures were made with Wynne's " Actinometer " 



on every possible occasion in the Easter vacation, '09. 

 Between March 29th and April 26th the actinometer 

 readings varied from two seconds on April 9th (bright 

 sunshine and a clear sky) to 135 seconds on March 31st 

 (sky overcast, no sun visible). The actinometer reading 

 was generally taken on the way out to sea, half-an-hour 

 or so before the plankton nets were hauled. Frequently 

 a second reading was taken on the return journey, and 



