THE ADAPTATION OF TRUOG'S METHOD FOR THE 



DETERMINATION OF CARBON DIOXIDE TO 



PLANT RESPIRATION STUDIES^ 



A. M. GURJAR 



Minnesota Agricultural Experiment, Station , St. Paul, Minn. 



In plant studies invohdng the phenomena known as respira- 

 tion, there is often occasion to determine the quantity of carbon 

 dioxide respired. This is regarded as an accurate, and at the 

 same time the most readily determinable, index of respiratory 

 activity available in laboratories not provided with an elaborate 

 respiration calorimeter. Satisfactory methods for the deter- 

 mination of carbon dioxide are accordingly ot interest to plant 

 physiologists and biochemists who are concerned with this phase 

 of phytochemistry. 



In the preliminary work on the study of the respiration of 

 stored grain which the writer is conducting, it became evident 

 that there were two requisites which the method for the deter- 

 mination of carbon dioxide must satisfy in order to be applicable 

 to this purpose. First, since the plant tissues are constantly 

 respiring, in determining the rate of respiration it is necessary 

 that the accumulated carbon dioxide be rapidly removed from 

 the respiration chamber. Second, the method must accom- 

 modate the wide variations in the quantity of carbon dioxide 

 to be determined, wdthout materially sacrificing accuracy. 



The customary, and most convenient method of determining 

 the quantity of carbon dioxide in the atmosphere of the res- 

 piration chamber, is to sweep COo-free air through it, and absorb 

 the respired CO2 in some form of absorption train. The con- 

 ventional absorption train, in which small potash bulbs are 

 employed, is of limited value because of the slow rate at which 



1 Published with the approval of the Director as Paper No. 58 of the Journal 

 Series of the Minnesota Agricultural Experiment Station. 



288 



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