238 CHAP. XXV. PHOTOSYNTHETIC STORAGE OF SOLAR ENERGY 



The storage of energy is calculated from the evolution of 

 oxygen by the plant, the carbohydrate-factor of which had 

 been very accurately determined. 



The photosynthetic efficiency of the leaves of Hydrilla 

 is fairly high, being as much as 7-4 per cent, in a vigorous 

 plant. 





