SEER Laas ee ee ee ee eee ae ee Pa Tee ee 
J Ou lal? 
Pernt y ee 1 ee ee eR a Mee PEE Ke ee 
iad gel AY ca ha a i te a 
_ Ig09] STON E—ELECTRICITY AND MICROORGANISMS 377 
charges on the germination of seeds and growth of seedlings we have 
observed that a very few minute sparks from a static machine caused 
the most marked stimulation. 
In regard to the influence of atmospheric electrical potential 
on growth, MonaHans’ found that when the air in a glass case is 
charged to a potential of about fifty volts, better results were obtained 
than when a higher potential was used. We endeavored, therefore, 
in these experiments to make use of current strengths approximating 
the optimum, or that strength which gave the best results in our pre- 
vious investigations with various organisms, except in those cases 
where strong static charges were given to milk for the purpose of 
ascertaining the degree of stimulation which would kill the organisms. 
‘The results obtained from these researches suggest many lines of 
work which might be followed, but we are obliged to discontinue them 
for the present. Electricity undoubtedly, in one way or another, plays 
a very important réle in plant life. Seed germination and growth of 
seedlings are greatly accelerated by feeble currents, but, unlike amides 
and enzymes, they are incapable of affecting the germinating capacity 
or of regenerating, as it were, the life in the seeds. The roots of the 
higher plants exist in a medium which is charged negatively, and the 
electrical potential of the air is often quite high within the limits of 
large trees. The electrical potential under the foliage of a tree is less 
than that at corresponding heights in the free atmosphere.® When, 
however, there is no foliage, the electrical potential under the branches 
of trees corresponds to that of the free air at equal heights, and there 
is reason to believe that the apices of leaves are merely so many points 
for the gathering and discharge of electricity. Minute currents of 
electricity exist in plants, and it is known that during certain periods 
trees discharge sparks from the apices of the leaves, and trees may 
tend to equalize differences in potential existing between the earth and 
4 air. Rain drops in falling become electrically charged, and as they 
_ Sather microorganisms in their descent through the air, these also 
_ Probably become affected. The remarkable influence of rain upon 
‘ Monanan, N. F., The influence of atmospheric electrical potential on plants. 
Ann, Rep. Hatch Exper. Sta. Mass. Agric. Coll. 16: 31-37 
° Stone, G. E., anD Monanas, N. F., Ann. Rep. Hatch Exper. Sta. Mass. Agric. 
3 Coll. 17: 13-3 
