246 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



tables shows that there is a minimum in November, December, 

 January, and February, increasing through the latter part of 

 February and March to a maximum in May and June and then 

 slowly falling off. Unfortunately measurements in the later 

 half of September and October are lacking which might have 

 shown the effects of the autumnal outburst of diatoms. 



Taking the figures available, there is a variation from 

 0-3 to 1-2 in November and December up to 2-8 to 3-0 towards 

 the end of April. 



The difference of about 2 c.c. of N/100 alkali for 100 c.c. 

 may not at first sight appear large. It may be taken as due to 

 carbon-dioxide as bi-carbonate in the water, and 2 c.c. of 

 M/100 carbon-dioxide per 100 c.c. is 2 c.c. of M/10 carbon- 

 dioxide per litre, this is 44 x 2 = 8-8 milligrams per litre. 

 Now the amount of carbon-dioxide which is photo-synthesised 

 between December and April is probably much greater than 

 this, because as the dissolved carbon-dioxide of the water is 

 attacked by the diatoms in presence of light to form oxygen 

 and build up organic carbon- compounds, the equilibrium 

 between sea-water and the overlying atmosphere is upset and 

 more carbon-dioxide is taken up from the air. To balance 

 this, the absorption coefficient of carbon-dioxide for sea-water 

 will decrease slightly at the somewhat higher temperature of 

 the later Spring. 



It might possibly be argued that the increased alkalinity 

 of the Spring was due solely to this physical^cause : that this is 

 not the case is shown clearly by a comparison of the values 

 of alkalinity with the temperatures of the sea-water in the 

 years 1912 and 1913 as shown in the curves reproduced. 

 It is observable that it is only in April that the temperature 

 begins to rise, whereas the alkalinity commences to rise in 

 February and March, and by the end of April is well on the 

 way to its maximum. 



Thus the table shows that in November, 1912, the value 



