370 BOTANICAL GAZETTE [NOVEMBER 
Feeble electrical currents and small static charges act as stimuli 
to bacteria in milk, increasing their numbers very perceptibly, and 
under certain conditions there may be after all some foundation for 
the old belief that milk sours more quickly during thunderstorms than 
at other times. Notwithstanding the fact that there may be other 
conditions during thunderstorms, such as warm and sultry weather, 
which may accelerate bacterial action, it is not difficult to imagine 
conditions under which milk might be stored which would subject 
it to electrical stimulation, thus increasing the number of bacteria 
and incidentally hastening souring. 
The influence of electricity on bacteria in soils 
Only a limited number of experiments was made by us relative 
to the influence of electricity on bacteria in soils. Careful bacterial 
analyses of soils are tedious operations and the methods followed in 
these analyses were similar to those recommended and used by 
CHESTER.? In all cases the counts were made on one gram of air- 
dried soil. In these experiments we made use of wooden boxes 
8X8X8 inches, inside measurements, which were filled with fairly 
good loam free from coarse material. The soil used was more or 
less compact, very fine sand (0.01™"—o0.005) predominating. It 
might be expected that the texture of the soil, as determined by the 
size of the particles, the amount of organic matter, and plant food, 
would exert an important influence on the bacterial flora, and the 
rather fine texture of the soil which we selected for this experiment’ 
would give results different from those that would be.obtained from a 
looser soil containing larger particles and having more air sa or 
one containing a larger amount of organic matter. 
In the box electrically treated were placed copper and zinc elec- 
trodes, each being 8X8 inches in size, and to these were soldered 
copper wires which were connected, thus forming with the soil a gal- 
vanic cell which furnishes a small current approximating the optimum. 
The percentage of water in the soil in each box was accurately deter- 
mined at the beginning of the experiment, and this same percentage 
was maintained throughout by adding sterilized distilled water. The 
experiments were carried on in the laboratory under conditions as 
— 
2 CHESTER, F. D., Delaware Agric. Exper. Sta. Bull. 65 : 61-65. 1904. 
