﻿CHEMICAL STIMULATION AND THE EVOLUTION OF 



CARBON DIOXID. 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 



XLIV. 



r 



Edwin Bingham Copelano. 

 \Conchided from p, gS^ 



As HAS already been noted, the interpretation of my results 

 with metallic poisons is uncertain. When the most of the 

 experiments were performed it was without a suspicion that the 

 CO3 evolved from the plants could be anything but an imme- 

 diate product of respiration. The results were presented in that 

 light to the Botanists of the Central States at their meeting of 

 December 1901. Since that time I have shown, and will pre- S 



sent the evidence in the following tables, that these metallic 

 salts can drive CO^ from solutions of such salts as are in the cell ^ 



sap. In any experiment, then, it may come directly from the 

 proteid or from the sap, and it probably comes from both. j 



Before the experiment began each subject of experiment was 

 left over night in its bottle, with a current of CO^-free air 



passing through it as rapidly as dunng the experiment. The ^O^ 

 evolved is expressed in cubic centimeters of normal acid for 

 each hour. The data of the first experiment, except the tem- 

 perature, are copied in full from my notebook, to illustrate the 

 nature of the record. The poison was applied by opening the 

 bottle and dropping in with a pipette enough of a concentrated 

 solution to give the desired strength. The bottle is open very s 



tew seconds. I have satisfied myself repeatedly, by putting in 

 water in the same way, that this introduces no error. The bottle j 



was at once shaken thoroughly to insure the equal distribution 

 of the poison. In each experiment except XXXVII Elodea was ^ 



used. 



The acceleration is rather great, considering the dilution ; 

 this is possibly due to the fact that the plants had been unusually 

 long in the laboratory, and were respiring very slowly. The 



160 [MARCH 



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