TABLE OF CONTENTS Xlll 



PAGE 



43. Starch Grains 112 



44. The behaviour of Starch towards Iodine 114 



45. The behaviour of Starch Grains in Polarised Light .... 115 



46. The Protoplasmic Structures of Plant Cells 116 



II. Disorganisation of the Molecular Structure 



47. The Influence of Low Temperatures on Plants 123 



48. The Changes which take place in Plants on Freezing .... 125 



49. Formation of Ice in Freezing Plants 125 



50. Death resulting from Exposure to too high a Temperature . . . 129 



51. Changes experienced by Plants in Death caused by Exposure to too 



high Temperatures 131 



52. The Effects of Mechanical Injury 133 



53. The Effect of Dessication on Plant Structures 134 



54. The Action of Electricity on Plants . . . ... . .135 



55. The Action of Poisons on Plants 137 



III. Molecular Processes in Plants 



56. Imbibition . . 139 



57. Diffusion and Endosmosis 143 



58. The Diosmotic Properties of the Cell-wall and of the Protoplasm . 145 



59. Turgor and Plasmolysis 149 



60. Isotonic Coefficients 151 



61. Magnitude of the Osmotic Pressure 154 



62. The Temperature of Plants 155 



63. Differences of Electric Potential in Plant 157 



IV. Movements of Gases in Plants 



64. Concerning the Behaviour of Gases in general 161 



65. The Intercellular System of Plants 164 



66. Lenticels 167 



67. Stoniata and their Importance in the Gas Exchange . . . . 168 



68. Positive and Negative Gaseous Pressure in Plants .... 175 



V. Absorption of Water by Plants 



69. The Absorption of Water from Soil by the Boots .... 185 



70. Absorption of Water by the Leaves 186 



71. Some Movements in Plant Structures related to their Absorption of 



Water . 187 



