Mar. 18, 1918 



Respiration of Stored Wheat 



703 



the sample containing 15.71 per cent of moisture, which was stored for 

 108 days, was about eight times as great as for freshly dampened wheat 

 containing that percentage of moisture. 



Table XIV. — Respiration of dampened wheat after storage at about 25° C. Incubated 



at 37.8° C. for four days 



Moisture per cent. . 



Number of days stored 



Carbon dioxid respired per 100 gra. of dry matter in each 24 

 hours mgm . . 



Carbon dioxid respired per 100 gm. of dry matter in each 24 hours, 

 of same lot of wheat 4 days after dampening mgra . . 



Carbon dioxid respired by naturally damp wheat from car lots, 

 of same moisture content mgm . . 



Lot B. 



15-72 

 108 



17. 00 



2. 17 



3-85 



Table XIV also shows a decided difference in the comparative rate of 

 respiration of wheat stored for a time in a warm room and that obtained 

 from freight cars. The latter had no doubt been damp for a longer time 

 than that which was dampened and held in the room. These data 

 suggest that not only does the period of dampness affect respiration, 

 but the conditions of storage may have an equally important effect. 

 The grain taken from cars was cold at the time, and had probably been 

 exposed to the cold atmospheric conditions of the preceding winter 

 months. If, as postulated by the writers, dextrose tends to accumulate 

 in the stored damp grain the rate of accumulation would depend upon the 

 temperature of the grain as well as upon the time elapsed. Accord- 

 ingly there may have been more substrate (dextrose) for the respiratory 

 enzyms in the grain which had been stored in the warm room than 

 there was in that stored out of doors during the winter months. A 

 series of experiments with both the period of dampness and the tempera- 

 ture of storage as variables have accordingly been begun, and the results 

 will be reported later in another publication. 



INFLUENCE OF TEMPERATURE ON THE RESPIRATION OF STORED 



WHEAT 



Pfeffer (1878) observed that the intensity of respiration increases 

 with the temperature until the latter begins to injure all the vital proc- 

 esses. Hoff {1896, p, 12^) stated that the rate of respiration increases 

 two or three times for each lo-degree rise in temperature in accordance 

 •vvith the usual rule of chemical reactions. Ziegenbein {i8gj) found 

 that temperatures above 45° C. were injurious 



Clausen {i8po) studied the respiration of germinating wheat at differ- 

 ent temperatures and found the optimum to be about 40° C. The rate of 

 respiration was 2.86 times as great at 10° as at 0° and 1.09 times as great 



