PERSONALITY OF PLANTS 
because their acids change into sugar under the 
influence of sunlight. 
Man seems to have outstripped the plants 
in the use of light, heat, electricity, and other 
physical forces, but the plants have more engi- 
neers among them than we imagine. In the 
fact that man has just learned to extract nitrogen 
from the air by the agency of electrical dis- 
charges, lies the probable explanation of how 
the plants have been doing the same thing for 
years. It is believed that the minute electrical 
discharges continually going on between the dif- 
ferent air strata make small quantities of nitro- 
gen assimilable for the plants. The micro- 
organisms which also furnish nitrogenous 
material to the plants may get nitrogen from the 
air in the same way. It is quite certain that the 
plants are affected by the chemical state of the 
atmosphere. 
Everyone knows what an important part 
light plays in plant physiology, but the fact that 
certain plants produce their own lights, while 
generally known, is not universally understood. 
The Austrian naturalist, Heller, was the first 
to demonstrate that the glowing of decayed 
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