7o8 



Journal of Agricultural Research voi. xii, no. n 



Table XVII. — Rate of respiration per day for several successive periods 



Period. 



Carbon dioxid 



respired per 



loo gm. of dry 



matter. 



First day 



Average rate per day for first 4-day period. . . 

 Average rate per day for second 4-day period 

 Average rate per day for third 4-day period. . 



Mgm. 



4. II 

 2.68 

 1.49 

 I. II 



RESPIRATION IN OXYGEN-FREE ATMOSPHERE 



That respiration may occur in the absence of oxygen was first dis- 

 covered by Rollo in 1798 {Hill, 191 3) in vi^orking with barley grains. 

 Other investigators confirmed this observation, and Pfefifer (1S78) 

 suggested the term "intramolecular respiration" for this class of phe- 

 nomena. Takahashi (1903) reported that rice can germinate in water 

 without the presence of sugar and in the entire absence of any air. 

 Hill (1913) determined the rate of respiration of water-soaked and 

 sterilized wheat in air, nitrogen, and hydrogen. The decrease in respira- 

 tion in a continuous current of hydrogen and nitrogen below that in a 

 continuous current of air was about 50 per cent in seeds sterilized in 

 alcohol and about 80 per cent in seeds sterilized in formalin. 



It appeared desirable to determine the effect of the elimination of 

 oxygen upon the respiration of stored wheat, and to this end the follow- 

 ing experiment was conducted: Two lots of wheat containing 15.6 per 

 cent and 17.6 per cent of moisture respectively were secured. A por- 

 tion of each lot was sealed in cylinders, the air was removed and replaced 

 by nitrogen. These lots and controls in ordinary atmospheric air freed 

 from carbon dioxid were then incubated for four days at a temperature 

 of 23.9° C. The data in Table XVIII show the rate of respiration in 

 the oxygen-free atmosphere to have been reduced to about two-fifths 

 of that in a normal atmosphere. 



Table XVIII. — Comparative rate of respiration in oxygen-free and normal atmosphere 



