CONTENTS. vii 
PAGE 
45. Why some seeds are sticky .72 
46. Three devices of Virginia knotweed . . . . . . 73 
47. Hooks rendered harmless till time of need ...... 74 
48. Diversity of devices in the rose family for seed sowing . . . 76 
49. Grouse, fox, and dog carry burs . . . . . . . .76 
50. Seeds enough and to spare 78 
Chapter VIII. — Man Disperses Seeds and Plants. 
51. Burs stick to clothing . 80 
52. Man takes plants westward, though a few migrate eastward . . 83 
Chapter IX. — Some Reasons for Plant Migration. 
53. Plants are not charitable beings 84 
54. Plants migrate to improve their condition ...... 85 
55. Fruit grown in a new country is often fair ...... 85 
56. Much remains to be discovered 86 
Bibliography 
89 
