704 Journal of Agricultural Research \o\. xii, no. h 



at 40° as at 30°. The average increase between 0° and 40° was 2.71 

 times for each lo-degree increase in temperature. 



Qvam (1906) found the rate of respiration increased up to at least 45° C, 

 which was apparently the highest temperature at which observations 

 were made. The grain was very moist, 100 gm. of water having been 

 added to 200 gm. of grain. 



Matthaei (1905) investigated the respiration of cherry-laurel leaves at 

 different temperatures and reported an increasing rate of respiration 

 between 5.8° and 33.1° C. At 5.8° 2 gm. of green leaves respired o.i 

 mgm. of carbon dioxid per hour, and at 33.1° the rate was 1.35 mgm. per 

 hour. 



The experiments of Duvel and Duval (1913) with shelled corn indicate 

 the relation of air temperatures to the heating of such material. Shelled 

 corn in transit and on track containing 16.9 per cent of moisture began 

 to heat and go out of condition between May 1 1 and June 3, 191 1, while 

 in the period from December 24, 1910, to January 20, 191 1, corn con- 

 taining 22 per cent of moisture gained only a few degrees in temperature. 

 The purely physical factor of heat loss into the cold winter atmosphere, 

 of course, served to reduce the rate of rise in temperature, but there was 

 probably a diminished rate of evolution of heat as well. 



Attention has been called by Bailey {1917a), to the influence of at- 

 mospheric temperatures upon the rate of heating of damp wheat. A 

 lot of wheat containing 16.5 per cent of moisture required but 11 days 

 to increase in temperature from 70° to 80° F., when the mean air temper- 

 ature was 62.1° F., while later in the year, when the mean air tempera- 

 ture was 44.3° F., another lot of wheat containing the same percentage 

 of moisture was stored 49 days before its temperature increased to the 

 same extent. 



Another comparison of the influence of temperature on the rate of 

 heating in storage was afforded by two lots of wheat put into bins at about 

 the same time and containing nearly the same percentage of moisture. 

 The initial temperature of one lot was 74° F., and of the other 70°. The 

 latter required over five times as long to reach a temperature of 80° as 

 did the former, owing to the slow increase in temperature at the outset 

 as contrasted with the rapid rate of increase as the temperature mounted 

 higher. 



To ascertain the relation of temperature to the rate of respiration in 

 stored grain, a large sample of Minnesota i69Bluestem wheat was damp- 

 ened until it contained 14.96 per cent of moisture. Aliquots of this 

 sample were sealed in glass jars and kept in a refrigerator until they were 

 used. This was done to minimize enzymic changes in the grain. The 

 necessary quantities were drawn from the refrigerator for incubation at 

 the several temperatures. 



The lowest temperature at which observations were made was 4°C., 

 and since the increase in rate of respiration between 4° and 25° was rela- 



