SEA-FISHERIES LABORATORY. 247 



lay below I/O, while in February it had risen to 1*2 to 1*3, 

 on April 8th it had reached 1*6, while the sea- water temperature 

 had not moved till April 19th when it had only risen by 1° F. 

 If the alkalinity at Life-boat Slip be taken from April 13th 

 till April 20th, 1913, the average is 2'4. Thus, at the point 

 where the temperature is only beginning to rise, the alkalinity 

 has nearly reached a maximum. The alkalinity of April 20th 

 is 3*0, compared with the figures 3*2 and 33 on June 14th 

 and 15th, 1913. On the former day the temperature is only 

 1° F. above the average March temperature, on the latter 

 days the temperature is 7° F. higher. The observations 

 in June, July and August, 1914, show that there is no increase 

 in alkalinity with temperature only. 



It is also to be noted that the great Spring outburst 

 of diatom activity appears before there would be time for any 

 effect of rise of temperature. Although the first upward 

 movement in temperature of- the sea-water and the enormous 

 increase in vegetable plankton lie close together in time, 

 it is to be remembered that the physical cause must have a 

 latent period ahead of the biological effect. The first movement 

 of temperature is very slight, and when it is remembered 

 that it must first stimulate growth, and then many succeeding 

 generations arise before there is a massive increase in the 

 vegetable plankton, it may probably be said that if the vegetable 

 plankton (and the increased alkalinity) were due to the increased 

 warmth of the water, then these would be found at least 

 a week later in time than the first rise in temperature. There 

 is, in fact, no such accordance observable, and it is far more 

 probable that the increased length of day and altitude of 

 sun, supplying a rapidly-increasing amount of solar light 

 energy, are the potent causes in producing the diatom outburst 

 and accompanying rise in alkalinity of sea-water. 



If the actual variation in alkalinity observed be taken 

 as a rough index of photo-synthetic activity, and as 



