44 STUDIES IN PLANT RESPIRATION AND PHOTOSYNTHESIS. 



In tables 10 and 11 and figure 8 are given the results of what was 

 termed the normal course of respiration. This represents the rate 

 of carbon-dioxid emission from Helianthus leaves in the dark at 24° 

 in nutrient solution containing no organic material, and indicates 

 the rate at which the carbohydrates in the leaves are consumed. 



40 45 



Figure 9. 

 Rates of respiration with and without glycocoll. The broken line represents the 

 rate of respiration of 8 leaves of Helianthus annuus at 24°; petioles in a nutrient solu- 

 tion containing no organic substances. Values taken from table 10. Solid line repre- 

 sents the rate of respiration of 8 leaves of Helianthus anmms at 24°, petioles in nutrient 

 solution containing 0.11 per cent of glycocoll. Values taken from table 19. The ordi- 

 nate represents mg. CO2 per hour per gram dry material, the abscissa the time in hours. 



As a counterpart to this, an experiment was carried out in which 

 the nutrient solution contained an amino-acid in order to determine 

 w^hat the influence of this is on the rate of respiration. The Helian- 

 thus leaves were taken from the same plant, a very large and strong 

 one, and were treated in precisely the same manner. The results 

 of this respiration experiment are given in table 19 and in figure 9, 

 the graphs of the two experiments, the one with and the other without 

 amino-acid. 



The analytical data representing the original condition of the 

 leaves and that at the end of the experiment, after having been 

 in the dark for 76.75 hours at 24°, with the petioles of the leaves 

 in nutrient solution containing 0.11 per cent glycocoll, are given in 

 table 20. 



