CHAPTER IV 



EFFECTS OF THE ELECTRIC LIGHT UPON 

 VEGETATION 



IT is well known that if a plant be kept in a dark 

 place it will lose its green color and pine away. 

 Experimenting with plants deprived of sunlight, 

 Professor C. W. Siemens found that if he substi- 

 tuted the light furnished by electricity, the plants 

 would keep in a large measure their green color 

 and grow almost as vigorously as with the sun 

 shining upon them. 



Recently a gardener, without any scientific abil- 

 ity, and without even the intention of experiment- 

 ing, arrived at a similar conclusion. He was 

 extremely puzzled one day to find that some 

 lettuce plants at one end of his greenhouse were 

 far in advance of those of the same age and variety 

 at the other end. He was finally led to conclude 

 that an arc-electric lamp, which had been burning 

 every night at the prolific end of the lettuce bed, 

 was the cause of his good fortune; and further ex- 

 perimentation proved his conclusion to be correct. 



The arc-electric lamp furnishes a light very 

 similar to sunlight, being, however, somewhat 

 richer in the rays beyond the violet and slightly 

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