378 BOTANICAL GAZETTE [NOVEMBER 
vegetation cannot be satisfactorily explained, in our opinion, by chem- 
ical analysis or by the various other conditions which prevail, and the 
idea that electrical stimulation plays an important réle here is not an 
improbable one. It is also not unlikely that during thunderstorms 
the bacteria in milk are affected, although two series of experiments 
made by us in exposing milk in sterilized metal vessels at different 
elevations, where the electrical potential showed considerable variation, 
were by no means conclusive. 
The effects of electrical stimulation on plant growth resemble more 
nearly those produced by heat, that is, in the tendency of the plant to 
assume a rather spindling growth; but this similarity in the method 
of reacting does not necessarily prove that electricity and heat are 
identical, since spindling growths in plants occur from other causes. 
The effects of electrical stimulation do not resemble those induced 
by light, since light inhibits growth; on the other hand, they more 
closely resemble the effects induced by lack of light (partial etiolation) 
and other forms of stimulation which may be produced by various 
agencies. Electricity stimulates seeds very perceptibly, causing an 
acceleration in growth, and probably has the same effect on spores, 
and in this way the number of bacteria in solutions might be increased. 
The process of cell division of bacteria and the budding of yeast are 
undoubtedly stimulated by electricity, which would result in an 
increase in the number of organisms and-an acceleration of the meta- 
bolic process. 
The effects of electrical stimulation, like other types of stimuli, are 
manifested shortly after application. With a current of optimum 
intensity a latent period occurs when no effect is discernible, and this is 
followed by an acceleration in growth and development. T he nature 
of the response is dependent upon the intensity of the stimulus as well 
as upon its duration; therefore to determine the period of duration 
of any particular response or its maximum period, the intensity and 
duration of the stimulus must be taken into consideration. Since the 
intensity and duration of the stimulus employed in these experiments 
differed materially, the response periods would also vary accordingly. 
As regards the manner in which electricity stimulates organisms, little 
can be said at the present time, and the problem is as difficult of solu- 
tion as the manner in which light, etc., affect the organisms. 
