CONTENTS 



§ 21. Tissues 



§ 22. Method of study of functions and organs 



PAGE 



22 

 23 



IV. The Roots 



§ 23. Functions of roots .... 



§ 24. Roots hold the stem firmly in position 



§ 25. Roots were first developed for fixation 



§ 26. Shrinkage of roots to aid in fixation . 



§ 27. The structure of the root 



§ 28. Climbing roots . 



§29. Stilt roots . 



§ 30. Columnar roots . 



§ 31. Keel or ballast roots . 



§ 32. Substances of which the soil is composed 



§ 33. The soil and root-hairs adhere . 



§ 34. Root-haii's and the region from which they arise 



§ 35. Action of roots which have been deprived of hairs 



§ 36. Can water be taken through the leaves ? . 



§ 37. The manner in which root-hairs take in liquids 



§ 38. Action of sugar 



§ 39. Another method of imitation of the action of root-hairs 

 § 40. Action of root-hairs on particles of mineral substance 

 § 41. The fate of the particles of soil .... 



§ 42. Food-material in the soil, and how the plant finds it 

 § 43. The tips of primary or main roots point downward 

 § 44. The tips of branches of the main roots are directed 

 zontally ........ 



§ 45. Sensitiveness of the roots to moisture 



§ 46. Roots bend away from light .... 



§ 47. The tip of the root is protected by- a sheathing cap 

 § 48. The sensitiveness of roots to touch with solid objects 



§ 49. The roots of air-plants 



§ 50. Parasitic roots 



§ 51. Method of germination and growth of the dodder 



§ 52. Union of roots with fungi 



§ 53. Roots as storage organs .... 



hori- 



