﻿174 



BOTANICAL GAZETTE 



[march 



sap and tap water. This is conspicuously true of the three metals 

 I have studied most thoroughly, Hg, Cu, and Zn; the more toxic 

 the metal, the weaker the solution required to set free measure- 

 able COg. But this parallel is too hazardous to be dwelt upon. 

 It appears also from the limited data at hand that the power to 

 decompose carbonates is disposed to be parallel to the power to 

 accelerate growth; for instance, Zn is very vigorous m propor- 

 tion to its toxicity in both respects. The power to set free CO^ 

 is also proportional in general to the bleaching power of the dif- 

 ferent metals, as demonstrated by the solutions left with Elodea 

 in them after the tests for toxicity. 



Having found no strong metallic poison which did not drive 

 CO2 from the tap water, T wondered if other poisons might pos- 

 sess the same power. The first tried were antipyrin and iodin, 

 both of which Jacobi found to accelerate respiration. I used 

 such concentrations as he had done. 



TABLE XXX. 



May 12. Test of iodin. Experiment bottle contains Elodea in 400^^ "Neptune 

 water. Control is 400*^*^ tap water. The air after passing each runs through a 

 small bottle containing 100 "^^ aq. dest. in which is more iodin than will dissolve. 



Time 



II : 19 



3:1: 



3 



7 



3:13 

 6:13 



-6 



-7 



13 



The iodin water 



43 



Experiment 



037 



poured into 

 0.068 



0.060 



the 



Control 



0.004 



other bottles 

 0.002 



0.000 



TABLE XXXI. 



May 10. Test of antipyrin. Experiment and control are same as in XXX. 



Time 



Experiment 



Control 



10:59-3^49 





0,030 



0.002 



3M9 



.25 ^ an 



tipyrin in both 



bottles. 



4 



3:49- 5:59 





0.047 



0.002 



5:59- 7:59 





0.050 



0.007 



7:59 9:32 



(13.55'^) 



0.047 



0.005 



9:32-11 :32 



N 



0.045 



0.000 



11:58 



HCl in both 



bottles. 



^f^ 



100 







II :58- 2:22 



(total C 



1 



03)0.925 



1.805 



