xii CONTENTS 



PAGE 



§ 86. White surfaces ... 71 



§ 87. The positions of leaves 72 



§ 88. Length of petioles 72 



§ 89. Leaf mosaic 72 



§ 90. Getting in the proper position 73 



§ 91. Helidtropic movements 73 



§ 92. Movements of leaves and stems in response to gravity . 74 



§ 93. Movements to avoid injury 74 



§ 94. Compass plants 75 



§ 95. Some plants have lost the power of manufacturing ehlo- 



rophyl 76 



§ 96. An association without chlorophyl 77 



§ 97. Pitchered leaves 77 



§ 98. Food-building in the lower forms 80 



§ 99. The leaf and water 81 



§ 100. Course of the water in the leaf 81 



§ 101. Transpiration 82 



§ 102. The vapor transpired 82 



§ 103. Measurement of the amount of water thrown oif by a 



plant 83 



§ 104. Sunlight increases transpiration 83 



§ 105. Regulation and control of transpiration .... 84 

 § 100. Wax or bloom as a means of prevention of excessive loss 



of water 84 



§107. Size of leaves and dryness of the air .... 84 



§ 108. Sleep movements 85 



§ 109. Velvety surfaces 85 



§ 110. Autumnal leaf fall 86 



§ 111. Separatory layer 86 



§ 112. The length of life of leaves 87 



§ 113. Growth of leaves 87 



§ 114. Wilting 88 



§ 115. Transplanting trees and herbs is attended by wilting . 89 



§ 116. Freezing and frosting 89 



§ 117. The air is colder on a frosty night near the surface than 



it is a few feet above it 91 



§ 118. Drainage of cold air ........ 92 



