328 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Sunshine and Plankton. 



As the view has frequently been expressed* that the 

 great vernal maximum in phyto-plankton is due to the 

 increase in sunlight at that time of year, it may he of 

 interest to give the results of the daily record of the hours 

 of sunshine made at the Port Erin Biological Station for 

 the last three years. We have them recorded in tabular 

 form for each day, but it will probably suffice to give here 

 the totals for the months : — 



Average Average 



1907. 1908. 1909. of of 



3 years. '08 and '09. 



January 24| 35 27 29 31 



February 58 28* 57£ 48 43 



March 113 83* 77^ 91£ 80* 



April 69£ 128-i 132| 1101 130* 



May 103 179 198* 160j 188| 



June 81 154* 160" 131* 157J 



Julv 143 111" 122^ 125£ 116| 



August 103* 118 130* 117} 124^ 



September 121* 60 122" 101J 91 



October 46j 81 61 62£ 71 



November 44 55£ 58* 52£ 57 



December 13£ 21 39* 24* 30}- 



As '07 may have been to some extent an abnormal 

 year — the sunshine in April is less than in March, and in 

 June is less than in any of the three following months — 

 we have added in the right hand column of the table the 

 monthly averages of the two years '08 and '09 ; and the 

 curves in fig. 14 show these averages and those of the 

 Bay plankton for the two years in question. The 

 similarity in these two curves is considerable — both show 

 the maximum in May, and a smaller but distinct elevation 

 in August-September, the plankton curve appearing to 

 follow that of the sunshine. 



* E.g., by Sir John Murray, and possibly by others before him. 



