STUDIES OF PHOTO-SYNTHESIS IN MARINE ALGM 121 



of sea water. The alkalinity tends to rise higher in the " shut " 

 jars in sunshine, because in the " open " jars in sunshine the atmo- 

 spheric carbon dioxide can enter through the muslin and partially 

 reneutralise the normal carbonates of magnesium and calcium 

 formed. 



TABLE. FIXATION OF NITROGEN BY MARINE ALGLE. EXPERIMENT OF 

 MARCH 28-ApRiL 5, 1919 (SEVEN DAYS' INTERVAL). 



It is of some interest to make a rough calculation of the quantities 

 of fixed carbohydrate, protein, or fat that these amounts of fixed 

 carbon dioxide, as estimated from the titrated increases of alkalinity, 

 would account for during the period of experiment. Taking the 

 mean of the two amounts of alkalinity upon the two days observed 

 viz., 13-3 and 9-7 one obtains 11-5. Deducting 2-5 c.c. for the 

 level of normal sea water at this period of the year the result is 

 9-0 c.c. of centinormal alkali resulting from photo- synthesis per 

 100 c.c. This change occurred in 800 c.c. in each set for a period 

 of seven days. This works out at 500 c.c. of centinormal alkali 

 during the period. Now 1000 c.c. of normal alkali corresponds to 

 12 grms. of carbon fixed, and on this basis the carbon fixed is 60 

 mgrms. This would correspond, on the basis of 45 per cent, of 

 carbon in carbohydrates, 60 per cent, in proteins, and 75 per cent. 



