﻿1903] 



CHEMICAL STIMULATION 



169 



concentrated. 



Less CO^ was evo 



Ived. I then put 700^*= of tap 

 water, without Elodea, in each bottle, and gave it the dose which 

 the Elodea and water had been receiving, with the same result. 

 The HgCl^ applied was: 



Exp. bottle, 0.7 



cc 



M 

 10 



Control, 7.0 



cc 



M 



10 



Total CO2 evolved in 24 hrs. 



0.535'' N. 



2.y]0^^ Normal. 



The CO 2 which can be washed from seven hundred cubic centimeters of tap 

 (lake) water varies, but is less than 0.310''*^ N. - 



result of the HgCla at least 



0.225*=^ N. 



0.310'^'^ N., leaving as 

 2.060'''^ N., which is 



more in both cases than the equivalent of the HgClo applied. 



Evidently no conclusions can be drawn as to the respiration 

 of Elodea, dead or alive, from work with Hg in the presence of 

 tap water. I therefore washed a lot of Elodea very thoroughly 

 in double distilled water for the next experiment. 



TABLE XXIV. 

 March 7. Tests of HgClo. 



Time 



Experiment 



11:09-3:39 



3:39 



M 



80000 



3 

 4 



39 

 39- 



4:39 

 6:33 



6:33 



M 



1000 run through wa 



HgCU in exp. 



6 



10 



33 

 24 



10 : 24 (15.85 hrs.) 



11 :37 



11:38 



M 



II :38-I2 : 40 



80000 



12 



40 



M 



12 :40- 8 : 00 



1000 



0.070 



HgCIg in exp. 



0.095 



0.076 



bottle. Plants re 

 ter to wash it. 



0.530 



Control 



0.059 



bottle. 



0.058 

 0.059 



HgCl;^ in con 



HgClg in con 



moved from control, and air 



(Total CO2), o.iio'^'^N 



(Total) 0.012 



trol bottle. 



(Total) 0.060 



trol bottle. 



(Total) 0.160'^'^X 



The last part of this experiment, with the water in which the 

 control plants had stood, shows that COo is driven from sub- 

 stances, presumably carbonates, as of lime, passed from the 



000 



plants into the water. The evolution of CO^ caused by - 

 HgCl^ was less excessive than when the plants were present ; 

 this I do not ascribe to a reaction with the proteid, but rather to 



the presence of the cell 



sap 



The difference is doubtless 



because of the limited amount of carbonates which had passed 



