278 



Journal of Agricultural Research 



Vol. XVII, No. 6 



period of nine days respiration continued more rapidly at 30° C. than at 

 25°. In storage tests made by the present writers during 191 8, 48 ears of 

 freshly picked green corn were placed in an air-tight can which had a 

 capacity of 46.6 liters. The corn displaced somewhat more than 20 

 liters, leaving about 26 liters of air. The can was then sealed, and loo-cc. 

 samples of the air were withdrawn at intervals through a stopcock and 

 analyzed by means of a commercial Orsat apparatus. In the results 

 thus obtained (see Table III) some error was caused by replacing with 

 fresh air that withdrawn for analysis; and the temperature of the cool 

 samples rose slowly, while that of the warmer sample fell somewhat 

 during the test. The differences, however, are far too great to leave any 

 doubt as to the facts. With corn at a temperature of 25° (picked near 

 noon on a warm day) there was over 19 per cent carbon dioxid at the 

 end of 4 hours. With corn at a temperature of 15° (picked in the morn- 

 ing) 8 hours were required to reach practically the same point, while 

 with still cooler corn the point was not passed in 10 hours.* 



Table; III. — Oxygen and carbon-dioxid content of air in which green sweetcorn had been 



stored in a sealed container 



TEMPERATURE OF GREEN CORN IN RELATION TO AIR TEMPERATURE 



In view of the rapidity with which green corn loses its sugar and the 

 relation of this loss to temperature, it is apparent that if the temperature 

 of the corn itself is near that of the air there must be a difference in the 

 extent of deterioration which would occur during a given interval in 

 different localities and that this difference must correspond to the dif- 

 ferences in climatic temperatures. Observations in Maryland and in 

 Maine indicate that the temperature of green corn on the stalk in the 

 shade is usually near that of the air while in the sun it is often well above 

 that of the air (see Table IV), 



It will be noted that in the cases cited in the table, which are typi- 

 cal of several others, the corn was 10° or more than 10° C, warmer in 

 the afternoon than in the morning.^ 



1 It may be of interest to note that the corn which had been kept for some time in an atmosphere defi- 

 cient in oxygen was of extremely poor quality. 



2 Compare in this connection the condition reported in small fruits (72). 



