X CONTENTS 



CHAPTER III 



THE WORK OF THE ROOTS 



PAGE 



The Roots as anchoring the Plant. The Roots supply the 

 Plant with Water. Roots require Air. Roots can only 

 take in dissolved Material. Etching Action of Roots 

 due to their Excretion of Carbon Dioxide. Elements 

 necessary to the Nutrition of Plants. Plants require 

 Combined Nitrogen ..... 42 



CHAPTER IV 



CHANGES OF COMPOSITION WITHIN THE 

 PLANT 



The Manufacturing, Resting, and Spending Stages in a 

 Plant's Development. The Course of Nutrition and 

 Migration in the Growth of Wheat. The Ripening of 

 the Grain. Storage and Migration in Root Crops. 

 Removal of Food Materials from the Leaves of Trees 

 as they Ripen. The Ripening of Fruit. Effect of Soil 

 and Climate upon the Composition and Quality of the 

 Crop ....... 59 



CHAPTER V 



THE ORIGIN AND NATURE OF SOILS 



The Weathering of Rocks to Soil. Solution of Rock 

 Materials in Water containing Carbon Dioxide. 

 Action of Frost. Transport of Soil by Rain and Run- 

 ning Water. Action of Worms. Approximate Analysis 

 of Soils. Properties of Clay and Sand. Chemical 

 Constituents of Soils. Soils and Subsoils , » 78 



