Contents. ix 



PAGE 



59. Structure of a succulent leaf 66 



60. Structure of a cladode 66 



61. Stomatal openings . 67 



62. Nature of transpiration ....... 68 



63. Evaporation from an artificial membrane . . .69 



64. Lifting power of a transpiring branch ..... 70 



65. Estimation of amount of water transpired . .. 71 



66. Guttation . .72 



67. Localization of transpiration ...... 73 



68. Hygrometer test for transpiration ...... 74 



69. Action of stomata ........ 75 



70. Path followed by sap in ascending from the roots to the 



leaves .......... 75 



71. Passage of sap through a woody stem 76 



72. Rate of movement of water through stems .... 76 



73. Diffusion streams in the plant ...... 77 



74. Air passages in plants . . . . . . .78 



75. Air passages through stems and leaves ..... 79 



76. Passage of air through lenticels and cortex .... 79 



77. Omose of gases 80 



V. NUTRITION. 



78. Composition of the body ....... 82 



79. Determination of organic and inorganic substances in plants 82 



80. Food elements of plants 83 



8 1. Presence of substances in solution in the soil ... 84 



82. Corrosive action of plants on minerals . . . .84 



83. Water cultures ......... 84 



84. Growth of plants in solutions lacking nitrates ... 86 



85. Growth with distilled water as a nutritive fluid ... 86 



86. Food-forming power of green leaves ..... 86 



87. Growth of plants in air free from carbon dioxide . . .87 



88. Properties of chlorophyl 87 



89. Formation of chlorophyl in light and darkness ... 88 



90. Absorption of light by tissues of plants .... 88 



91. Red color in leaves ......... 88 



92. Arrangements tor concentrating rays of light upon chlorophyl 



layers .......... 89 



93. Exhalation of oxygen by green plants ..... 89 



