692 



Journal of Agricultural Research 



Vol. XII, No. n 



continuous structure, and the possibilities of diffusion are decidedly 

 reduced under such conditions. The exact percentage of moisture below 

 which this discontinuous structure exists in a normal wheat kernel is 

 not known; it probably varies with the percentage of gluten in the grain 

 since gluten possesses a greater water-imbibing capacity than starch. 

 Increasing the moisture content above the maximum at which discon- 

 tinuity exists results in the formation of a gel through which diffusion 





AS 



OF /'TO/SrU/PS 



Fig. I. — Graph showing the relation of the moisture content of wheat to the rate of respiration. 



can occur. Further increases in moisture content up to maximum imbi- 

 bition produce progressively less viscous gels, and correspondingly in- 

 crease the possible rate of diffusion. Since the rate of respiration in 

 grain doubtless depends in part upon the rate of diffusion between the 

 various kernel structures, it follows that the less viscous the gelatinous 

 material of which the cell contents are composed, the more rapid the 

 production of heat through respiration. To restate, the production of 

 heat is dependent upon the activity of the oxidizing enzyms of the 



