6 DYNAMICS OF PHOTOSYNTHESIS 



The experiment was started in the following manner. When 

 everything (plants, sea water, and tubes) had come to the tempera- 

 ture of the bath, the plants were placed in the tubes, the rubber tubes 

 were clamped shut, and the tubes were then placed in the bath so that 

 they were about half an inch below the surface of the water, making an 

 angle of about 20° with the surface, and exposed to direct sunlight. 



Under these circumstances the alga receives abundant sunlight for 

 photosynthesis. The amount of sunlight is affected by reflection 

 from the surface of the water and the amount of reflection is influ- 

 enced by the movement of the water due to stirring. But this is a 

 fairly constant factor and of negligible importance. The effect 

 of stirring can be obviated by placing a sheet of glass in contact with 



McClendon, J. F., Gault, C. E., and MulhoUand, S., Carnegie Institution of Wash- 

 ington, Publication 251, 1917, 21. 



0.2 M boric 0.05 M borax. pH 



acid. 



cc. cc. 



10 9.24 



1.0 9.0 9.11 



2.0 8.0 8.98 



3.0 7.0 8.84 



4.0 6.0 8.69 



4.5 5.5 8.60 



5.0 5.0 8.51 



5.5 4.5 8.41 



6.0 4.0 8.31 



6.5 3.5 8.20 



7.0 3.0 8.08 



7.5 2.5 7.94 



7.7 2.3 7.88 



8.0 2.0 7.78 



8.5 1.5 7.60 



9.0 1.0 7.36 



9.4 0.6 7.09 



9.7 0.3 6.77 



By plotting the cc. of borax as ordinates and the pH values as abscissae a curve 

 is obtained from which intermediate values can be obtained by graphic interpola- 

 tion. From the pH values found in sea water 0.21 must be subtracted on account 

 of the 'salt error." In the present investigation these values were carefully 

 checked by means of the hydrogen electrode. 



