Feb., 1922] 
ARNDT — ^THE GROWTH OF FIELD CORN 
51 
In the solution cultures, pint Mason jars and colorless cylindrical 
museum jars of 900 cc. capacity were used. These were treated with clean- 
ing fluid for several hours before each experiment. The jars were com- 
pletely covered with opaque black paper. A loose shell of stiff light-brown 
cardboard was placed over this. Flower pots were used for the sand 
cultures. These were thoroughly impregnated with heated paraffin and 
then well coated on the inside with a thin layer of the same. The sand 
was procured from the Whitall Tatum Company. It is the brand known 
as "Juniata." It was prepared as recommended by the Committee on the 
Salt Requirements of Representative Agricultural Plants. It had a water- 
holding capacity of 32 percent. It was kept at 60 percent of its water- 
holding capacity throughout the experiment by the method recommended 
by the above-named Committee. 
The relative transpiration of the plants grown in the various solutions 
was determined from the amount of water added daily to replace the water 
which had been lost. The relative transpiration here reported is based 
on the loss for a certain period immediately preceding the time when the 
plants were harvested. During this period the evaporating power of the 
atmosphere was determined by standardized spherical white and black 
atmometer cups. To keep the conditions of light and temperature as 
nearly uniform as possible for all cultures, as no rotating tables were avail- 
able, the plants were shifted daily in a systematic manner so that each 
plant occupied the same position for about the same period during the 
experiment. 
Each solution culture contained four plants. Five plants were grown 
in each pot in the sand cultures. In most cases the cultures were run in 
duplicate series, so that the relative growth is based on the total weight of 
eight or ten plants. The weights reported in the tables are based on the 
mean weight of one plant. 
Germination 
The seed used was carefully selected for uniformity of size and shape. 
The seed was soaked for 15 minutes in tap water, drained, and allowed to 
stand at room temperature for two hours. It was next treated for 15 
minutes with a 5 percent calcium hypochlorite solution (5 g. per 100 cc). 
This was removed by washing the seed several times with boiled tap water. 
It was finally soaked for 12 hours in a shallow covered dish in just sufficient 
boiled water to cover the seed. After soaking, the seeds were distributed 
on filter paper in germinating dishes and covered with a layer of filter 
paper. The dish was placed in the greenhouse, covered with glass, and 
flooded once a day with water. When the radicles were one centimeter 
long, the seeds were removed to a paraffined germination net made of coarse 
netting. This was stretched over an inverted twenty-liter bell jar, and 
filled with a solution of one tenth the concentration of the solution R2S3 
