32

4. Diagram of a single villus 33

5. Enlarged figure of four cells in the villus membrane 33

6. A bit of muscle showing blood-vessels 36

7. A bit of bark showing cellular structure 61

8. Successive stages in the division of the developing
egg 63

9. A typical cell 65

10. Cells at a root tip 66

11. Section of a leaf showing cells of different shapes 66

12. Plant cells with thick walls, from a fern 67

13. Section of potato 67

14. Various shaped wood cells from plant tissue 68

15. A bit of cartilage 68

16. Frogs' blood 69

17. A bit of bone 69

18. Connective tissue 70

19. A piece of nerve fibre 70

20. A muscle fibre 71

21. A complex cell, vorticella 71

22. An amoeba 73

23. A cell as it appears to the modern microscope 86

24. A cell cut into pieces, each containing a bit of
nucleus 89

25. A cell cut in pieces, only one of which contains any
nucleus 90

26. Different forms of nucleii 93

27 and 28. Two stages in cell division 96

29 and 30. Stages in cell division 98

31 and 32. Latest stages in cell division 100

33. An egg 103

34 and 35. Stages in the process of fertilization of the
egg 104

36 and 37. Stages in the process of fertilization of the
egg 105

38, 39, and 40. Stages in fertilization of the egg 106

41 and 42. Latest stages in the fertilization of the egg 109

43 and 44.