Feb. 3,1923 Use of A Iternating Temperatures in Seed Germination 317 
TEMPERATURE CHANGES WITHIN THE GERMINATING CHAMBERS 
As was anticipated, the temperature changes varied considerably in 
different parts of any given chamber. The heat imparted to the wet 
blotters and the seeds passed inward from the copper walls of the cham¬ 
ber; in cooling them the radiation was in the opposite direction. Natu¬ 
rally, the temperature changed more rapidly and therefore attained 
HOURS ; FROM T/ME HEAT/NG WAS BEGUN . 
Fig. 14.—Curves showing changes of temperature within wet blotters in a germinating chamber 
which was heated three hours, then held at a nearly constant temperature for three hours, and 
finally cooled during three hours. 
wider extremes near the top, bottom, and side walls of the chamber 
than near the center of the chamber. Furthermore, the rates of heating 
and cooling, especially of the seeds in the central parts of a chamber, 
were more rapid when only four thicknesses of blotting paper were used 
on each tray than when eight thicknesses were used, and were more rapid 
in the air between the seed trays than within the blotters themselves. 
These differences are illustrated in Figures 13, 14, 15, and 16. 
