50 



STUDIES IN PLANT RESPIRATION AND PHOTOSYNTHESIS. 



It should be noted that in the foregoing experiment, unlike the 

 two previous ones, there is an increase in the carbohydrate-content 

 and the increase in the amino-acids is very small. With these facts 

 in mind, the results of the rates of respiration as plotted in figure 12 

 are noteworthy. The rapid drop between the fifth and tenth hours 



Table 27. — Rate of COi emission of 15 leaves Canada Wonder hean at 25°; -petioles in 

 nitrogeiv-free nutrient solution containing 7 per cent d-glucose. 

 CO2 absorbed in Ba(0H)2 solution 0.1169 normal, showing resistance of 53.2 ohms in cell with 

 constant of 1.2255 at 25°. 



Figure 12. 

 Rate of respiration of 15 

 leaves of Canada Wonder bean 

 at 24°; petioles in nitrogen-free 

 solution containing 7 per cent 

 d-glucose. Values taken from 

 table 27. The ordinate repre- 

 sents mg. CO2 per hour per 

 gram dry material, the abscissa 

 the time in hours. 



of the experiment is probably due to the fact that the sugar from 

 the nutrient solution had not yet got into the leaf in sufficient 

 quantity to cover the loss through respiration. Thereafter the 

 rate of CO2 emission shows a rapid rise, soon followed by a regular 

 decline far below the initial rate, until the fortieth hour, when there 



