ILLUSTRATIONS xiii 



PAGE 



28. Scheme of Cross between Red-Eyed Male Dro- 



sophila and White-Eyed Female . . .100 



29. Diagram of Chromosomes in Protenor . 102 



30. Chromosomes of Drosophila . . .104 



3 1 . Figure illustrating Cross between White-Eyed Male 



Drosophila and Red-Eyed Female . . 105 



32. Figure illustrating Cross between White -Eyed 



Female Z';roj(?^;^z7a: and Red-Eyed Male . . 107 



33. Chromosomes of Abnormal Female Z'rwo^^z'/a . 109 



34. Scheme illustrating Cross between Black Tom 



Cat and Yellow Female . . .110 



35. Scheme illustrating Cross between YellowTom 



Cat and Black Female . .110 



36. Pedigree of Colour-blinds . . . .111 



37. Scheme of Inheritance for Silver Hen . . . 113 



38. Normal Sterile X Cretin Fertile Sweet-Pea . . 115' 



39. Scheme illustrating Distribution of Chromosomes . 135 



40. Diagi'am illustrating Linear Arrangement of 



Chromosomes in Drosophila . . . .138 



41. Drosophila; Black Vestigial x Grey Normal . 139 



42. Diagram illustrating " Crossing Over " . . 143 



43. Drosophila; Black Normal x Grey Vestigial 145 



44. Single and Double Stocks . . . . .154 



45. Fg Generation ex Silky Hen x Brown Leghorn 



Cock 160 



46. Graphic Representation of Weight Distribution in 



Fj and F2 Generations from Sebright-Hamburgh 

 Cross 165 



