DETERMINATION OF PHOTOSYNTHETIC EFFICIENCY 235 



The carbohydrate-factor for oxygen enables us to 

 calculate the amount of carbohydrate formed under the 

 action of light. The energy stored is found from the number 

 of calories corresponding to the heat of combustion of the 

 product. 



The coefficient of transmission is determined from the 

 sequence of radiometric observations (1) and (3), and of the 

 calorimetric determinations (2) and (4). The equality in the 

 values of the coefficient obtained by the two independent 

 methods serves as a test of their reliability. 



Typical example.— The mass of water in the Calorimeter, 

 plus the water equivalent, is equal to 5-16 grm. 



Determination of coefficient of transmission.— Rise of tem- 

 perature in the Calorimeter : 



Deflection G under full radiation . 5° mm - 



g ,, transmitted radiation . . 20 mm. 



Intensity of full radiation D by Radiometer 166 divisions, 



transmitted radiation d „ 67 



20 

 Coefficient of transmission by Calorimeter - =0-40 



50 



„ Radiometer ^ = 0-40 



Coefficient of absorption =1 — 0-4 = 0-6 



The coefficients of transmission and absorption deter- 

 mined by the two methods are thus identical. 



Energy absorbed in photosynthesis. — This is ascertainable 

 from the calorimetric determinations given in (2) and (3). 



Energy absorbed in photosynthesis = H — h. 



The rise of temperature under full radiation for three 

 minutes caused 50 mm. deflection of the Galvanometer, 

 while the transmitted radiation caused a deflection of 

 20 mm. (50 mm. = i° C). 



r 5° — 20 



Energy absorbed H — h in 3 minutes = 5-10 X — — — 



= 3-096 cal. 

 or 1 • 032 cal. per minute. 



