7o REMAINING OF ENERGY PENETRATING SURFACE 

 20 40 60 80 



PHS. DURING AN AVERAGE DAY. RELATIVE UNITS 

 10 20 30 



f Compensation Level 



40 



Fig. 212 A, % light absorption in sea water of different absorp- 

 tion co-efficients. B, Relative photosynthesis in Macrocystis on an 

 average day in waters of different absorption coefficients (A above). 



(After North.) 



395 



