EXPERIMENT STATION BULLETINS. 



305 



The value of such a system of cross-breeding is two fold : 



(1) Cross-fertilizing of plants results in increased vigor; and, 



(2) The bringing together of plants from ears selected for proven 

 strong qualities ought to produce even greater vigor. 



IMPROVING QUALITY. 



This has reference to changing the physical characteristics of the ear 

 and kernel and the chemical composition of the kernel. Physical changes 

 are brought about both by selection and by cross breeding. At the 

 present time selection is employed to accomplish chemical changes, and 



Fig. 10. — A study of the structure of the kernel of corn, showing the location of the germ with the 

 embryo, and the distribution of the starch and the horny starch. The Ught portion is the starch. 

 Ihe very dark portion is the horny starch. 



(a) Shows especially well the position and appearance of the embryo. 



(c) Shows a Iar;?er proportion of horny starch than does (b). 



(d) Shows a cross section of a kernel like (b) just above the horny starch. 



(e) Shows a cross section of the same kernel just below the upper end of the horny starch. 



(f) Shows cross section of the same kernel at upper end of germ. 



the chemical changes usually sought are in the starch, oil and protein 

 content, depending, of course, upon whether the corn is grown for 

 feeding purpose or for the starch factory. 



The oil is obtained from the germ, and the quantity of oil depends 

 upon the size and upon the quality — chiefly on the size — of the germ. 



Fig. 10 shows the structure of kernels of corn. The light portion of 

 the kernel is the starch, the darkest portion is called the horny starch. 

 The greater part of the protein comes from the horny starch; therefore, 

 the greater the amount of horny starch, the greater the amount of 

 protein. 



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