riv CONTENTS 



PAGB 



Metabolism a« a Source of Energy 76 



Kinds of Food Used in Metabolism 77 



Metal>oIism in Animals is often Wasteful 78 



Warm-blooded Animals 79 



Cold-blooded Animals 79 



Waste Materials are Produced in Connection With Metabolism 80 



Waste in (Irowth Metabolism 80 



Waste in Functional MetalK>lism 81 



Waste Must be Gotten Kid of if Metabolism is to Continue. . . 81 



Metabolism Goes on in Every Cell 82 



The Services of Supply 82 



CHAPTER IX 

 The Transportation System in Animals 



Conditions Favoring Cell Activity 83 



Need of Transportation 83 



Cell Diffusion 84 



Cell Surface and Body Surface 84 



Water Frontage in Lower Animals 85 



The Flatworm Transportation System 85 



Moderately Complex Transportation Systems 86 



Circulatory System of Higher Animals 87 



The Blood 88 



Lymph 88 



Lymphatic or Absorbent Vessels 89 



Summary 90 



CHAPTER X 

 The Food-Preparinq System 



Digestion 91 



Classes of F oods 91 



Foods Proper 92 



Alimentary Tract 92 



Manufacture of Enzyms 93 



Saliva 94 



Gastric Juice 94 



Pancreatic Juice 94 



The C'omposition of Proteins 94 



The Intestinal Juice 95 



Movements of the Alimentary Tract 96 



Absorption 96 



CHAPTER XI 

 Rgbpiration and the Disposal op Wastes 



Respiration 98 



Diffusion of Cr ses 98 



Respiratory Organs 99 



Gilla 100 



