xii TABLE OF CONTENTS 



SECTION II 



PRODUCTION AS RELATED TO CLIMATE 

 AND SOILS 



CHAPTER V 



FAGEB 



Relation of Climatic Factors to Growth . . . 57-67 

 Relation of climatic factors to growth, 58 — Length of 

 growing season, 59 — Relation of sunshine to growth, 61 

 — Relation of rainfall to growth, 64. 



CHAPTER VI 



Relation of Soils to Growth 69-73 



Causes of low production, 70 — ^Classification of corn 

 soils in the United States according to productiveness, 70. 



SECTION III 



IMPROVEMENT AND ADAPTATION OF THE 

 CORN PLANT, AND ENVIRONMENT 



CHAPTER VII 



Early CrLTURE 77-84 



Development of varieties, 78 — Early methods of modi- 

 .fying varieties, 80 — Natural selection and acclimatization 

 in producing varieties, 83. 



CHAPTER Vin 



Improvement op Varieties 85-93 



Type of ear, 85 — Type of plant, 86 — Systems of selec- 

 tion, 88 — Results with mass and pedigree selection, 89 — ■ 

 Selection for composition, 91. 



