LIST OF ILLUSTRATIONS 



FIG. 

 29. 

 30. 



3i- 

 32- 

 33- 

 34- 

 35- 

 36. 



37- 

 38. 

 39' 

 40. 

 41. 

 42. 

 43- 

 44- 

 45- 

 46. 



47- 

 48. 

 49. 

 50. 

 5i- 

 52- 

 53- 



54. 



55- 



56, 



57 

 58 



59 

 60 



61 



Young ear showing silks ready for pollination 



Young ears showing silks at different stages of development 



Young ear with fully developed silk . ., 



Young ear with husks removed .... 



Bisexual tassel of a sucker-shoot .... 



Bisexual tassel (bearing small ears) of a sucker-shoot 



Bisexual tassel on main stem . . . ■ 



Bisexual ear ....■•■ 



Bisexual ear ....••• 



Silks injured by larvae ..... 



Blind ear, on which the silks have failed to develop 



Tassel of sugar maize ...... 



Spikelets of the maize plant. (After De Vries) . 



Pollen grains of maize . . . . • 



Effect of complete or partial lack of pollination . 



Effect of partial pollination . . . . • 



Young ear showing homology of husks 



Young ear showing ovaries and styles (" silks ") . 



Two-lobed ear ....... 



Bifid ear ........ 



Branched ear of Hickory King .... 



Branched ear of Ladysmith .... 



Pod maize (Zea Mays var. tunicata) . 



The style or silk ....... 



Diagram showing course of pollen tube through style to ovule. (After 

 drawing by C. S. Ridgway, in Duggar's Southern Field Crops) 



The embryo-sac in maize at time of fertilization. (After drawing by 

 F. E. Lloyd in Duggar's Southern Field Crops, by permission of 

 The Macmillan Company) . . . . . • 



Four secondary ears developed from the nodes on the shank of a single 

 ear ........••■• 



Secondary ear developing from a node of the shank .... 



Maize plants developing two ears ....... 



Left-hand twist of rows ......... 



Right-hand twist of rows ......... 



Enlarged section through hull of maize grain. (From Passmore and 

 Webber) 



Variation in shape of maize grains. (From U.S. Department of Agri- 

 culture Year-book) ......... 



85 

 86 



87 



89 

 89 

 90 

 90 



9i 

 92 



95 

 96 

 96 



97 

 98 



99 



100 

 101 



IOI 



102 

 102 

 103 

 IO4 



I06 



107 



no 

 III 



112 

 Il6 



117 



119 



CHAPTER V. 



62. " Nubbins " of Hickory King ; one cause of poor yields 



63. Desirable and undesirable types of Hickory King 



64. Increasing yield by increasing depth of grain 



65. A desirable type for selection ..... 



66. Increasing yield by increasing number of rows at the butt 



67. Result of breeding for reduction of sulci 



68. Variation in shape and size of grain in the same breed 



69. Shortening the growing season ..... 



70. Result of weak stalks ....... 



71. A heterozygous F 2 ear ...... 



72. Segregation of characters after crossing Pj and F 1 ears 



73. Segregation of characters in F 2 ears .... 



74. Segregation of characters in the F 3 (seed) generation : all-black ears 



75. Segregation of characters in the F 3 (seed) generation : black-and-whit 



ears ........... 



76. Segregation of characters in the F 3 (seed) generation : all-white ears 



77. Part starchy, part wrinkled grain ....... 



78. Xenia in colour 



135 

 136 

 149 

 150 



151 

 152 



153 

 155 

 157 

 164 

 165 

 166 

 167 



169 

 170 

 176 

 178 



