40 ELECTRICITY IN AGRICULTURE 
by the passage of the electricity from the points into the 
air, and the current introduces them in a fresh condition 
into the capillary tubes of the plant. In this way the 
effect of the electric air-current can be reduced to a purely 
mechanical one. 
We do not maintain that any other effects than the 
mechanical may not occur ; but our experience does not go 
so far that we can say anything with certainty on this point. 
The effects of the two currents can be determined in the 
following way :— 
The negative current going from the earth to the plants 
facilitates the drawing-up of water with the dissolved 
matter through the roots of the plant to its capillary tubes, 
and thus produces a stronger circulation of the saps.. 
The positive current brings to the plants the different 
elements, and introduces them through the openings in 
their capillary tubes in such a way as to promote vegetation. 
This latter effect is, as mentioned ‘above, very much more 
effective than the former. 
In the above-related experiments the effects were pro- 
duced by an artificial electric air-current ; but, as also men- 
tioned above, a continual electric current is going upwards 
or downwards, certainly in the polar regions and in our 
latitudes, but probably everywhere ; and this current must 
evidently exercise a greater or lesser influence on the life of 
vegetables in the way we have endeavoured to show. 
Electricity takes a much larger part in the life of vege- 
tables than it has been presumed to do till now. The 
amount or value of this influence cannot be determined 
without examining more exactly the electric currents of the 
atmosphere. The methods used at present for this pur- 
pose cannot lead to this knowledge. New methods must 
-be introduced, and this question will be one of the most — 
significant in the scientific programme of the future. 
We cannot say that the question regarding the influence of 
the artificially produced electric air-currents has reached 
