under Various Electrical Conditions . 
J 53 
amount of carbon dioxide produced consequent upon the application of the 
discharge, the differences being always less than 5 per cent. (Table XVI). 
Experiments with discharge from a mercury-platinum contact electrode, 
giving a current density of 3 to 6 x io -6 amperes, were attempted, but no 
quantitative observations were made owing to the tendency of sparks to 
pass from the discharge wire to the plants, thereby causing them to shrivel. 
The effect of the gaseous products of the discharge in air upon seed- 
lings was then tested, the method being identical with that used for similar 
tests with seeds (p. 149). 
The discharge in the first chamber was maintained for periods varying 
from five minutes to two hours, the products being drawn into the second 
chamber containing the seedlings. 
The result was a rather unexpected one, namely, an apparent increase 
in the carbon dioxide produced, in one case a matter of 67 per cent. When 
the discharge was on for only five minutes the increase was inconsiderable 
(Table XVII). 
In addition, when the plants were examined after the experiment, it 
was found that the chlorophyll in the upper portions had been bleached by 
the oxidizing agents produced in the atmosphere by the discharge. 
If a vessel of turpentine was introduced into the chamber containing 
the seedlings, the deleterious effect of the gases was obviated, leaving the 
plants unaffected by continued application of discharge in the first chamber. 
Some controls under very rigorous conditions were carried out to 
ascertain whether the products of the discharge — the oxides of nitrogen in 
particular — were liable to vitiate the foregoing experiments by neutralizing 
some of the baryta solution independent of carbon dioxide production. 
Accordingly the products of discharge in an empty chamber were led 
(1) directly through baryta solution in a Pettenkofer ; (2) through a chamber 
containing dead peas, and then through baryta solution. The period in 
each case was thirty minutes, and the current density was approximately 
6 x io -5 amperes, the highest employed in any experiments. 
The result showed a maximum production of acid equivalent to 
o-ooii grm. carbon dioxide in the case where the gases were led directly 
through the alkali. Where peas intervened — the normal case — the carbon 
dioxide equivalent was 0*0002 grm. (Table X). 
Thus in the experiments upon the effect of the products of discharge 
upon seedlings the apparent increase in the amount of carbon dioxide 
evolved was probably due to the acidity of the oxides of nitrogen present, 
but in the experiments with seeds these gases were absorbed before reaching 
the baryta solution. 
As a result of this work we have reached the conclusion that the electric 
discharge has no direct effect upon the respiration of germinating seeds 
and seedlings, but under laboratory conditions, wherein the plants are in a 
