vin THE FOOD OF PLANTS 



CHAPTER III 



THE NATURE OF THE SOIL 



PAGE 



The Soil contains Sand and Clay . . . .21 



The Improvement of Clay Soils . . . .22 



The Amount of Water in the Soil . . . .22 



The Soil should not contain too much Water . . 24 



The Soil contains decaying Remains of Plants called 



Humus . . . . . .25 



The Subsoil contains little Vegetable Matter . .26 



The Way the Soil has been Formed . . 27 



CHAPTER IV 



THE SUBSTANCES OF WHICH A LEAF IS COMPOSED 



Four-fifths by Weight of the Leaf is Water . . 30 



The Leaf contains Water, Charcoal, and Ash . .31 



Part of the Food of Plants from broken-down Rocks . 31 



The Effect of Farming on the Soil . . . .31 



How the Exhaustion of the Soil is Prevented . . 33 



The Ash contains among other Substances Potash and 



Phosphoric Acid . . . . .34 



CHAPTER V 



HOW PLANTS OBTAIN FOOD FROM THE AIR 



The Seed obtains Food from the Air ... 40 



The Food obtained from the Air is Charcoal . . 40 



The Air is Altered by Burning Substances . . .43 



The Air is Changed by the Breathing of Animals . . 44 



Vitiated Air restored by Plants in Sunlight . . 45 



