Xll 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. Heliotropic 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 chlo- 



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 off by a 



plant 83 



104. Sunlight increases transpiration 83 



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

 106. 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 



