THE ENERGETICS OF PHOTOSYNTHESIS 65 



sorbed energy in blue (4360 A). The energy absorbed by the other pigments 

 is also photosynthetically active, although the efficiency is much less. This 

 explains why the Cjuantum requirement is higher in blue than in red and 

 vellow. 



The quantum requirement 4.4 (see Table 4) corresponds to an efficiency 

 value lower than that obtained by Warburg and Negelein in their first experi- 

 ments (see § 21). We find that 



_ chemical energy _ 112000 _ ^ 

 quantum energy 4.4 X 43300 



In later experiments utilizing an improved technique (see § 29), Warburg el al. 

 found considerably lower values for the quantum requirement, i.e., higher 

 values for the efficiency. In experiments lasting several hours (6440 A) they 

 obtained a value as low as 2.91. Such a low quantum requirement corre- 

 sponds to the efficiency 



112000 



2.91 X 44400 



= 87% 



As the quantum requirement in photosynthesis is not dependent on the wave- 

 length, it is possible to obtain at a wave-length 6800 A (highest v^alue in red) 

 an efficiency of 



^ 112000 ^ 

 ' 2.91 X 41400 "^^ 



If the efficiency t] were 100%, the theoretical quantum requirement would be 



112000 

 \l^ X 42100 



1/<P = 2.7 



From equation 2 the following general equation for the efficiency can be 

 obtained 



112000 



. , ^ 2.86 X 10« 



\I<P X 7 



0.04A 



The efficiency of photosynthesis, at the quantum requirement 3, is very 

 high indeed by comparison with other biological processes. We shall see 

 later that other investigators found values between 8 and 12 for the quantum 

 requirement. According to these figures, the correctness of which we shall 

 discuss later, the efficiency would be about 25%. This is a very low figure. 

 Warburg's assertion (50) that the genius of living Nature cannot be satisfied 

 with such a low photosynthetic efficiency has been proved in his more recent 

 work (see § 29 and § 30). According to Burk (9), the fact must be envisaged 

 that in a perfect Nature photosynthesis is perfect too (see Addendum). 



