July IS, 1919 



Carbohydrate Metabolism in Green Sweet Corn 143 



the times required to perform equal amounts of work at all temperatures, 

 and not by comparing the amounts of work performed in equal times_ 

 In other words, we must compare the times required at the different 

 temperatures to bring the process to the same stage. We are thus com- 

 paring stages where the ratio between the reacting material and the 

 products is the same. Osterhout ^ has recently emphasized this point 

 in a "Note on measuring the relative rates of life processes." 



In order to make it possible to determine, on this basis, the relative 

 rates of sugar loss at the different temperatures, the experimental results 

 in Table I can be easily interpolated by a simple graphic method, to 

 be described later, if they can be expressed in curves all starting from the 

 same point. 



This could be decided only alter a careful consideratioti of all the 

 factors involved. If mass action alone were responsible for the gradual 

 decline in the rate of sugar loss, then, at a given temperature, the average 

 rate of change in any unit of time would be proportional to the sugar 

 concentration. For a range of original sugar from about 4.5 to 7 per 

 cent and of water from 78 to 80 per cent this was found to be the case 

 for the first 48 hours of storage even at 30° C. (Table II). 



Table II. — Proportion of sugar lost during first 48 hours of storage at jo° C. 



The sugar loss ceases when an appreciable amount of sugar is still 

 present. Therefore, the speed of the counter process, that is, the for- 

 mation of sugar, becomes a factor to be reckoned with when the processes 

 have nearly reached an equilibrium. If at the beginning of storage the 

 percentage of sugar in ear i is considerably greater than in ear 2, the 

 latter would reach the equilibrium position sooner than ear i. At the 

 end of 72 hours of storage at 30° C. ear i might still have 2 per cent sugar 

 while in ear 2 the sugar content might be only i per cent. The sugar 

 loss in ear 2 being nearer the equilibrium point, the speed of the counter 

 process would be greater in this ear than in ear i. Therefore, during the 

 next 24 hours the proportionality between the sugar lost and the sugar 



' Osterhout, W. J. V. note on measuring the relative rates of life processes. In Science. 



n. s., V. 48, no. 1233, p. 172-174, 3 fig. 1918. 



