CONTENTS 



Chapter 

 VI. The Nitrogen Cycle 

 Sources of Nitrogen 

 The Protoplasm Cycle 



VII. The Soil and the Sap 



Composition of the Soil. Leaf Mould 

 Life in the Soil .... 

 The Sap 



VIII. Food 



Chemistrj^ of Food ..... 

 Variety of Foodstuffs and Feeding Habits 



IX. Digestion 



Alimentary Canal 



Body-cavity 



Digestion . 



Hormones and Vitamins 



Calories . 



Appetite . 



X. Respiration 



Plant Respiration 

 Respiratory Organs in Animals 

 Dust and Sand 

 Haemoglobin . 

 Anaerobes 



XI. Movement 



Movement of Plants 

 Amoeboid Movement 

 Movement of Animals 



Flight 



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 41 



43 

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48 



57 



58 



87 

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 96 



99 

 101 

 105 

 106 

 112 



115 

 121 

 122 



128 



