THE VIABILITY OF RADISH SEEDS 303 
an oven maintained at 104° C. In the experiments requiring a reduc- 
tion of the water content of air-dry seeds, the amount of water present 
was diminished by heating, first in an oven at 60° C. and later in one 
at 100° C. Samples were treated with the desired temperature when, 
upon weighing, it was found that the water content of the seeds had 
been reduced to the desired amount. To increase the water content 
the air-dry seeds were exposed to a saturated atmosphere until they 
had absorbed the amount desired in a particular experiment. This 
method proved satisfactory when only a slight increase in water 
content of the seeds was desired. When a considerable increase was 
necessary, the air-dry seeds were soaked in tap water at 20° C. until 
they had absorbed the required amount. The seeds, superficially 
dried between towels, were placed in flasks and allowed to stand for 
a time to permit the water to penetrate uniformly before heating. 
A momentary immersion of the dry seeds in 95 percent alcohol was 
found beneficial in that it allowed a quick and uniform wetting of the 
coats when the seeds were placed in water. 
The seeds were germinated on plaster of Paris blocks twelve 
centimeters square and three centimeters thick. The surfaces of these 
blocks were crosschanneled so that there were one hundred inter- 
sections suitable for the hundred seeds used in each test. The blocks 
containing the seeds were placed in fiber tubs and water added to a 
depth of two centimeters. The tubs were covered and kept in a 
dark room at approximately 23° C. A daily record of the number of 
germinated seeds was made, and this continued for fourteen days. 
Experiments and Discussion 
All the earlier investigations in this field were carried on with 
very dissimilar seeds of widely different, and in no case definitely 
determined, water content. In no instance was an attempt made 
to find the effect of high temperatures acting for definite periods of 
time upon series of like seeds of different but known water contents. 
Radish seeds (Icicle, Black Spanish Winter, and Crystal Forcing), 
with an initial water content of from 4 percent to 71 percent as indi- 
cated in Tables I, II, and III, were placed in the flasks already 
described and heated for thirty minutes at temperatures (50° C. to 
125° C.) indicated at the head of the tables. After heating for this 
period they were placed on the blocks for germination. The results 
