696 



Journal of Agricultural Research 



Vol. XII, Mo. II 



Table IV. — Respiration of white winter wheat "■ from Michigan, incubated at 27-8°C. 



for four days 



<J Weight per bushel of sample, 59 pounds. Weight per 1,000 kernels, 37.73 gm. Nitrogen on dry basis, 

 1.53 per cent. 



Table V. — Interpolated quantity of carbon dioxid respired per unit of time and material, 

 at even percentages of m,oisture 



Class of wheat. 



Hard spring . . . . 

 Soft red winter. 

 White winter. . . 



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



per cent 

 moisture. 



Mgm. 

 O. CO 



49 



13 

 per cent 

 mojsture. 



Mgm. 

 C. K& 



■ h 



. 60 



14 

 per cent 

 moisture. 



Mgm. 

 0.68 

 .81 

 ■83 



IS 

 per cent 

 moisture. 



Mgm. 

 I- 13 

 1-37 

 4- 15 



16 

 per cent 

 moisture. 



Algm.. 

 2. 72 

 3-84 

 9-85 



17 

 per cent 

 moisture. 



Mgm,. 



IO-73 



15-51 

 25.18 



RELATION OF THE RELATIVE PLUMPNESS OF THE WHEAT KERNEL 

 TO THE RATE OF RESPIRATION 



It is generally recognized that the velocity of enzym action conforms 

 quite closely to the law of mass action. Thus any condition which 

 affects the quantity of either the substrate or the enzym will cause 

 variations in the rate of the reaction. Since respiration is occasioned 

 by enzyms, the rate of respiration of the wheat kernel should vary with 

 these conditions. 



A shriveled condition of the wheat kernel is due generally to factors 

 operating during the later stages of kernel development. The trans- 

 location of reserves to the kernel is interfered with by rust, drouth, 

 desiccation by hot winds, or some other agency; and an incomplete 

 filling of the endosperm results. According to Brenchley {igog), the 

 germ portion of the kernel is developed earlier than the endosperm, 

 and tends to escape injury from the agency causing shrunkenness of 

 the endosperm more than does the latter. The diminished size and 

 weight of the shriveled kernel is therefore due principally to the decreased 

 quantity of endosperm. 



The enzymic activities of the kernel seem to be mainly invested in the 

 embryo. This was discussed in one of the foregoing paragraphs. In 

 the embryo of the shriveled wheat berry the enzyms are probably repre- 

 sented practically as they are in the normal kernel. In instances where 

 the average weight of the individual kernel is only about half the normal, 



