14 



DYNAMICS OF PHOTOSYNTHESIS 



is KM. Hence if we start in the morning with 5 alone there will be 

 produced each minute KM and all of this will be transformed into P 

 except what is present at any moment as M. Hence the amount of 

 P produced in the time T is KMT — M. 



When M has attained its constant value, we may, for convenience, 

 put if = 1. The rate of increase of P is then constant and we find 

 from the table that it takes 20.4 minutes to produce one unit of photo- 



M=l< 



Fig. 5. Curve to illustrate that, as M decomposes in monomolecular fashion to 

 form P, the amount of M left at any given time, T, is e~^'^ and the amount of P 

 is l — e~^^. The abscissae represent time; the ordinates the amount of M. 

 At the start of the reaction 71/= 1. 



synthesis ; hence ii^Afr = 1. Substituting in this equation the values 

 of M and T we have 20.4 A' = 1, whence K = 0.049. 



At the start of the reaction the value of M is ; this gradually in - 

 creases to 1 and remains constant. Durihg this period of increase 

 the value of M may be calculated as follows : When M has reached its 

 constant value (M = 1) let us suppose that the reaction S -^ M sud- 

 denly stops while M -^ P continues; we shall find that if T minutes 

 have elapsed after this occurrence, the amount of M which has dis- 



-KT 



appeared is 1 — e (see Fig. 5). If the reaction S -^ M had not 



