Chapter 1

Man 170

APPENDIX 187

INDEX 191

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ILLUSTRATIONS

PLATES

PLATE PAGE

Gregor Mendel _Frontispiece_

I. Rabbits _To face_ 60

II. Sweet Peas " 64

III. Sheep " 78

IV. Sweet Peas " 80

V. Fowls " 107

VI. Butterflies " 146

FIGURES IN TEXT

FIG.

1. Scheme of Inheritance in simple Mendelian Case 21

2. Feathers of Silky and Common Fowl 30

3. Single and Double Primulas 31

4. Fowls' Combs 32

5. Diagram of Inheritance of Fowls' Combs 37

6. Fowls' Combs 39

7. Diagram of F_2 Generation resulting from Cross between two White Sweet Peas 46

8. Diagram illustrating 9 : 3 : 4 Ratio in Mice 52

9. Sections of Primulas 55

{xii} 10. Small and Large-eyed Primulas 56

11. Diagram illustrating Reversion in Pigeons 67

12. _Primula sinensis_ × _Primula stellata_ 68

13. Diagram illustrating Cross between Dominant and Recessive White Fowls 72

14. Bearded and Beardless Wheat 75

15. Feet of Fowls 76

16. Scheme of Inheritance of Horns in Sheep 76

17. _Abraxas grossulariata_ and var. _lacticolor_ 99

18. Scheme of Inheritance in _Abraxas_ 102

19. Scheme of Inheritance of Silky Hen × Brown Leghorn Cock 105

20. Scheme of Inheritance of Brown Leghorn Hen × Silky Cock 106

21. Scheme of F_1 (ex Brown Leghorn × Silky Cock) crossed with pure Brown Leghorn 107

22. Scheme for Silky Hen × Brown Leghorn Cock 108

23. Scheme for Brown Leghorn Hen × Silky Cock 109

24. Diagram illustrating Nature of Offspring from Brown Leghorn Hen × F_1 Cock 110

25. Scheme to illustrate Heterozygous Nature of Brown Leghorn Hen 111

26. Scheme of Inheritance of Colour-blindness 117

27. Single and Double Stocks 122

28. F_2 Generation ex Silky Hen × Brown Leghorn Cock 127

29. Pedigree of Eurasian Family 130

30. Curve illustrating Influence of Selection 159

{xiii} 31. Curve illustrating Conception of pure Lines 162

32. Brachydactylous and Normal Hands 170

33. Radiograph of Brachydactylous Hand 170

34. Pedigree of Brachydactylous Family 173

35. Pedigree of Hæmophilic Family 175

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For although it be a more new and difficult way, to find out the nature of things, by the things themselves; then by reading of Books, to take our knowledge upon trust from the opinions of Philosophers: yet must it needs be confessed, that the former is much more open, and lesse fraudulent, especially in the Secrets relating to _Natural Philosophy_.

WILLIAM HARVEY, _Anatomical Exercitations_, 1653.

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