THE HORTICULTURAL SOCIETY OF NEW YORK 



Days 



21 



28 



Fig. 4- 



—Growth curves for the following vegetable seedling plants grown in flats- 

 A-Xj and B-Xj Tomato Chalk Early Jewel. 

 A-Xg and B-Xg Celery White Plume. 

 A-X^ and B-Xy Lettuce California Cream Butter. 

 A-X. and B-X„ Onion Yellow Globe Danvers. 



35 



The results obtained at Columbia University and described in 

 "Preliminary studies in the Response of Plants to Artificial Light," 

 Illuminating Engineering Society publication, 1923, show a marked 

 increase of growth with plants treated with artificial light plus 

 sunlight. 



PROCEDURE OF TEST 



Several thousand vegetable seedlings raised in flats and a large 

 number of flowering plants started from cuttings, raised in pots, 

 were placed under ten 500-watt, iio-volt Mazda C clear lamps. 



Seed was planted in pots and flats on February 19, 1923, and the 

 artificial light experiment started on March ist, 1923 at 9 p. m. 

 and was discontinued on April 4, 1923 (thirty-five days). 



With each plant, flat or pot of seed tested under the lamps 

 there were exact duplicates, tested under sunlight alone. 



39 



