22. Percolation experiment. To show the relative powers
of soils to take in water falling on the surface 41

23. Bottles used in place of the lamp chimneys in Figs.
22 and 24 44

24. Capillarity of soils. To show the relative powers of
soils to take water from below 44

25. Water-absorbing and water-holding powers of soils 45

26. Capillary tubes. To show how water rises in small
tubes or is drawn into small spaces 48

27. Capillary plates 48

28. A cone of soil to show capillarity 49

29. To show the relative amounts of film-moisture held
by coarse and fine soils 49

30. To show the effect of a soil mulch 56

31. Soil temperature experiment 57

32. Charts showing average temperature of a set of dry
and wet soils during a period of five days 60

33. To show the value of organic matter 61

34. Soy-bean roots, showing nodules or tubercles 64

35. Garden-pea roots, showing tubercles or nodules 65

36. To show that seeds need water for germination 72

37. To show that seeds need air for germination 72

38. To show that seeds need air for germination 73

39. A seed-tester: two plates and a moist cloth 80

40. A seed-tester: a plaster cast with cavities in the
surface for small seeds 80

41. Germinating corn-kernel and bean 81

42. To show how the bean-plant gets up 82

43. To show how the corn-plant gets out of the soil 82

44. To show the use of cotyledons 83

45. To show the use of the kernel to the young corn-plant 86

46. To show how deeply seeds should be planted 87

47. Operations of seed-planting 88

48. A collection of planting machines 89

49. Spading-fork and spade 92

50. A wood beam-plow 93

51. A slip-nose share and a slip-nose 96

52. A straight knife coulter