xviii LIST OF ILLUSTRATIONS 



PAGE 



79. DIAGRAM ILLUSTRATING COMPLEMENTARY FACTORS .... 418 



80. DIAGRAM ILLUSTRATING BEHAVIOR OF INHIBITORY FACTOR . . 421 



81. DIAGRAM SHOWING SOME POSSIBLE COMBINATIONS IN F 2 WHEN 



FI OF FIGURE 80 Is INBRED 422 



82. DIAGRAM SHOWING THE HETEROZYGOTE SITUATION . . . .422 * 



83. DIAGRAM ILLUSTRATING THE ACTION OF A SUPPLEMENTARY 



FACTOR 423 



84. DIAGRAM ILLUSTRATING NILSSON-EHLE'S EXPLANATION OF THE 



15:1 RATIO IN F 2 OF HYBRID BETWEEN RED- AND WHITE- 

 GRAINED WHEAT 425 



85. ANOTHER METHOD OF VISUALIZING NILSSON-EHLE'S 15:1 RATIO 426 



86. DIAGRAM OF NILSSON-EHLE'S 63 : i RATIO 427 



87. SEX-LINKED INHERITANCE OF WHITE AND RED EYES IN Droso- 



phila 434 



88. RECIPROCAL CROSS TO THAT SHOWN IN FIGURE 87 . . . .435 



89. DRAWING SHOWING THE FOUR PAIRS OF CHROMOSOMES SEEN IN 



THE DIVIDING EGG OF Drosophila 436 



90. DIAGRAM SHOWING THE LOCATION IN THE FOUR PAIRED CHROMO- 



SOMES OF Drosophila, OF THE GENES FOR VARIOUS MENDELIZ- 

 ING CHARACTERS, AS DETERMINED BY MORGAN 437 



91. SEX-LINKED INHERITANCE OF BARRED AND UNBARRED (BLACK) 



PLUMAGE IN POULTRY 438 



92. RECIPROCAL CROSS TO THAT SHOWN IN FIGURE 91 . . . . 439 



93. DIAGRAM TO SHOW THE MECHANISM OF CROSSING OVER. . . 440 



94. AN ARMADILLO EGG ABOUT Six WEEKS AFTER FERTILIZATION, 



SHOWING THE QUADRUPLET FOETUSES 451 



95. A TYPICAL OPPOSITE-SEXED PAIR OF CATTLE TWINS .... 455 



96. A PEDIGREE OF BRACHYDACTYLISM 460 



97. A PEDIGREE SHOWING TRANSMISSION OF CATARACT .... 461 



98. A PEDIGREE SHOWING HEREDITY OF FEEBLE-MINDEDNESS . . 463 



99. ANOTHER PEDIGREE SHOWING HEREDITY OF FEEBLE-MINDED- 



NESS 464 



100. PEDIGREE SHOWING HEREDITY OF INSANITY 465 



101. PEDIGREE SHOWING HEREDITY OF INSANITY AND NEUROTIC 



TENDENCY 465 



