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