69 — 



A comparison of the fréquence table ol' Conferva with the 

 sunshine data therefore appears toshow thatan unusual amount 

 ofsunshine al the timeof the year at which Conferva tends (o 

 attain ils maximum, exerts a harmful influence (see also the 

 eharl on p. 60). 



We believe that the sunshine also affords some explanation 

 for the unusually long persistence of Conferva in 1908. The 

 number of hours of sunshine from January to May of 1908 was 

 5 ( .n'» hours, i. e. 61 hours less than in the corresponding period 

 of 1906, 69 hours less than in 1907, 176 hours less than in 1909; 

 moreover 1908 was the only year in which no abnormal amount 

 of sunshine occurred during the first four months, such as 

 would tend to give a check to the development of the Conferva. 

 It may be therefore that the lack of bright sunshine during the 

 first four months of 1908 gave such an impetus to the develop- 

 ment of the Conferva that it persisted longer than usual, 

 although June of 1908 was exceptionally sunny (*>. 



Table to show the occurrence of Conferva and Ophiocy- 

 tium in Bartons pond, 1906-1910 (2) . 



It may be well however to draw attention to the fact once 

 again that compétition also cornes into play in determining the 



(1) See fbotnote 1 on p. 7 1 . 



(2) Regarding the symbols, see footnote 1 on p. 54. Ophiocytwm was not 

 observée! in 1910. 



