448 BOTANICAL GAZETTE [DECEMBER 
about five feet from the plants. Ordinary enamelled reflectors of 
the deep bowl type were used to throw the light downward. The 
lamps used were of the 200 watt and 1000 watt sizes; the latter is 
considerably more economical in operation than the smaller size. 
These lamps are rated to burn rooo hours, but average about 
3000 hours. They were burned twenty-four hours per day, so that 
one set of lamps was sufficient for four months or more. Breakage 
of the lamps occurred the most frequently when the current was 
turned off and the filaments allowed to cool. The continuous 
burning seemed to greatly increase the life of the lamps. 
Plants grew well, set good seed or produced tubers in the 
continuous illumination. It seems unnecessary to have a period 
of darkness to allow translocation of the assimilate from the leaves. 
Several intensities of light were used and the plants grew in each. 
The lowest intensities of about 25 foot candles in dark corners 
produced much better growth than was obtained in the greenhouse 
during the winter. Analyses of the carbohydrate and protein 
contents of the plants are being made. 
In one room 8X11 feet a great variety of cereals was grown, 
including twenty varieties of wheat, fifteen varieties of oats, eighteen 
varieties of barley, eight varieties of rye, six varieties of flax, several 
hybrids of wheat and of oats, and a few other test plants. The room 
was lighted by lamps with a total capacity of 3200 watts and 
distributed uniformly: The lamps required about 0.6 watt to 
4 7 X3200 
produce one spherical candle. Then = 67,021 lumens 
total flux. On account of the light absorption and inefficiency of 
the reflectors, only about 60 per cent of this light reaches the ground, 
so that there are 40,212 lumens spread over the area 8X11 feet, 
giving an intensity of about 457 lumens per square foot. In this 
light winter rye headed at about 24 inches; Kota wheat at 28 
inches; Bluestem wheat at 23 inches; Aurora oats at 17 inches; 
Manchuria barley at 17 inches. These plants were grown in 5-inch 
pots. Usually six or eight kernels were all that set in a head of 
wheat, but these were plump and full of starch. The temperature 
was maintained automatically at about 14°C. by cooling with 
outside air. It was unnecessary to use any heat in this room 
other than that produced by the lights. The light is doubly 
