1922] HARVEY—ARTIFICIAL LIGHT 451 
bloomed at 48 inches, and set tubers weighing as high as 180 gm. 
each. White sweet clover set some seed when 4o inches high. 
A number of weeds were allowed to grow, and they all set abundant 
seed. Boltonia asteroides bloomed when 54 inches high; Cheno- 
podium ambrosioides set seeds profusely at 35 inches; Silene latifolia 
bloomed at 16 inches but did not set seed; Stellaria media bloomed 
and set seed at 16 inches; foxtail grass (Alopecurus) set abundant 
seed at normal height. 
Under the todo watt lamp shown in fig. 2 the light intensity 
was about 4188 lumens per square foot. Plants under this light 
were very stocky, and showed effects of too much heat. The leaves 
of cabbage were very turgid and stiff. The plants were rotated to 
equalize light and temperature, and to decrease the heating effect 
of the light on surfaces directly exposed. 
All of the plants in these rooms except cabbage bloomed, and 
many produced good seed, although the illumination was continuous. 
It seems then that the period of illumination is not the factor which 
determines whether a plant will bloom or not. The results obtained 
by GARNER and ALLARD‘ may have been produced by a modification 
of the conditions of nutrition of their plants by variation in the 
length of the day. It is possible to obtain seed from a great variety 
of plants as here shown, although the illumination is continuous, 
and the intensity is approximately the same for’all plants in one 
room. 
Summary 
A great variety of plants, including wheat, oats, barley, rye, 
flax, buckwheat, white sweet clover, peas, beans, lettuce, and a 
number of common weeds were grown from seed to maturity in 
continuous artificial light, and all set good seed. Potatoes, toma- 
toes, red clover, alsike clover, squash, and Silene bloomed, but did 
not set seed. Potatoes produced tubers of good size. All of the 
plants tested did not require a certain period of illumination to 
cause them to bloom. It is possible to produce seed from plants 
in winter independent of sunlight, and at no very great expense. 
UNIVERSITY FARM 
St. Paut, Minn. 
* GARNER, W. W., and Atrarp, H. A., Jour. Agric. Res. 18:553-606. 1920. 
