xxiv LIST OF ILLUSTRATIONS 



FIG. PAGE 



16. Average length of the crop-growing season in days (U. S. 



Weather Bureau) ...... 78 



17. Interior view of a one-seed drop cotton planter (B. F. 



Avery & Sons Plow Co.) . . . .111 



18. Adult boll-weevil showing characteristic teeth on front legs 



which serve to distinguish this insect from other 

 weevils (Paddock) ...... 127 



19. Showing variation in size of boll-weevils (Paddock) . . 128 



20. Root distribution of corn at silking time (U. S. Dept. 



Agr.) . . . ". Vv 152 



21. Structure of corn plant at different stages of growth 



(after Bull) .... . . . .155 



22. Ear of corn showing tendency to laminate (after Harsh- 



berger) . . 158 



23. Botanical parts of the corn kernel and its integuments 



(after Harshberger) *. . . . .159 



24. Cross section of the outer portion of a grain of corn (after 



Webber) 160 



25. Illustrating development of corn stem (after Montgomery) . 167 



26. Illustrating the process of fertilization of the corn flower 



(after Montgomery) ...... 169 



27. Illustrating structure of corn kernel at pollination (after 



Crosthwait) . ; ; 170 



28. Cross-section of corn ear looking toward the base (after 



Winton) 171 



29. Illustrating the relationship between gama grass, teosinte, 



and corn (after Montgomery) . . . . 175 



30. A small ear of the pod-corn group .... 178 



31. An ear of white rice pop corn (U. S. Dept. Agr.) . . 178 



32. An ear of White Pearl pop corn (U. S. Dept. Agr.) . . 179 



33. A good ear of the flint-corn group (U. S. Dept. Agr.) . 180 



34. A good ear of dent corn (U. S. Dept. Agr.) . . .181 



35. An ear of the sweet-corn group ..... 182 



36. Showing the average angle of declination of corn ears after 



five generations of breeding for erect ears (111. Sta- 

 tion) . .188 



37. Showing the average angle of declination of corn ears after 



five generations of breeding for declining ears (111. 

 Statio"n) . 189 



