CONTENTS ix 



XV. WATER REQUIREMENTS FOR PLANT GROWTH 183 



Water Requirements of Plants Precipitation and Plant 

 Growth Ecological Classification and Crop Production, 

 Xerophytes, Mesophytes, Hydrophytes Plant Succes- 

 sions Plant Geography Crop Zones. 



XVI. RELATION OF CARBON DIOXIDE TO PLANT GROWTH 192 



Source of Carbon Composition of the Air Absorption of 

 Carbon Dioxide The Cells the Laboratories of the Plant 

 Composition of Chlorophyll Relation of the Stomata 

 to Carbon Dioxide Photosynthesis Efficiency of the 

 Food-making Machine -Sugar and Starch Transformation 

 and Migration Formation of Other Foods. 



^XVII. MINERAL NUTRIENTS AND NITROGEN 199 



Ash Content of Plants Origin of Minerals The Functions 

 of the Mineral Nutrients Chemical Analysis of Plants and 

 Soils Nitrogen Source of Nitrogen Ammonification 

 Nitrification Nitrifying Organisms Other Soil Organ- 

 isms Water Cultures. 



XVIII. METABOLISM DIGESTION TRANSLOCATION GROWTH 209 



Metabolism Digestion Translocation Assimilation 

 Growth Phases of Growth Irritability Plant Move- 

 ments Tropisms Relation of Plant Organs to Sunlight. 



XIX. RESPIRATION AERATION FERMENTATION 221 



Respiration Respiration and Photosynthesis Respira- 

 tion and Starvation Diffusion and Absorption of Oxygen 

 Aeration Fermentation Anaerobic Respiration . 



XX. TEMPERATURE AND LIGHT 228 



Environmental Factors Plant Geography Temperature 

 Maximum, Optimum and Minimum Temperature for 

 Germination Freezing Light Relation of the Plant to 

 Sunlight Relationship of Leaves to Sunlight Influence 

 of Light on Plant Distribution. 



XXI. PLANT EVOLUTION 235 



Geological Record Geographical Record Theories of 

 Evolution Lamarck Darwin Mendel DeVries, 



