CONTENTS 



CHAPTER I. A LESSON IN CHEMISTRY . . ...... 1 



Chemical elements. Atoms and molecules. Chemical formulas. 

 Chemical compounds. Distribution of the elements. Elements found 

 in plants. Potassium. Sodium. Magnesium. Calcium. Aluminum. 

 Iron. Manganese. Oxygen. Hydrogen. Nitrogen. Chlorine. 

 Carbon. Phosphorus. Sulphur. Silicon. Practical exercises. 



CHAPTER II. ORIGIN OF THE SOIL .......... 11 



What the soil is. Depth of the soil. The subsoil. Origin of the soil 

 and subsoil. Weathering. Weathering by decomposition. Weather- 

 ing by disintegration. Work of glaciers. Modifications of the bed 

 rock. Table of rocks. Changes in mantle rock. Practical exercises. 



CHAPTER III. TYPES OF SOILS ........... 25 



Named for their origin. Sedentary soils. Lacustrine soils, 

 soils. Volcanic soils. Colluvial soils. Glacial soils. Alluvial soils. 

 Soil constituents. Sand and clay contrasted. Loam. Alkali soils. 

 Acid soils. A test for acid soils. Artificial soils. Practical exercises. 



CHAPTER IV. CONDITIONS AFFECTING SOIL FERTILITY . 38 



Structure. The air. Air in the soil. Temperature. Variations in 

 temperature. Other factors that modify temperatures. The Fahren- 

 heit and centigrade scales. Precipitation. Water in the soil. The 

 water table. Drainage. Irrigation. Dry farming. Physiologically 

 dry soils. Practical exercises. 



CHAPTER V. THE ORGANIZATION OF THE PLANT .... 55 



The great plant groups. The regions of the plant. Cellular structure 

 of the plant. Roots. Taproots. Structure of the root. Root hairs. 

 Osmosis. The stem. Structure of the stem. Buds. Leaves. Internal 

 structure of the leaf. Formation of plant food. Transpiration. 

 The flower. Pollination. The fruit. The seed. Life cycle of plants. 

 The rest period of plants. Genera, species, and varieties. Scientific 

 names. Practical exercises. 



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