VIII. DIGESTION OF A MOUTHFUL OF BREAD 35

IX. BAD HABITS IN EATING 39

X. A DROP OF BLOOD 46

XI. WHY THE HEART BEATS 48

XII. HOW TO KEEP THE HEART AND THE BLOOD HEALTHY 56

XIII. WHY AND HOW WE BREATHE 63

XIV. HOW TO KEEP THE LUNGS HEALTHY 75

XV. THE SKIN AND WHAT IT DOES 81

XVI. HOW TO TAKE CARE OF THE SKIN 88

XVII. THE KIDNEYS AND THEIR WORK 91

XVIII. OUR BONES AND THEIR USES 93

XIX. HOW TO KEEP THE BONES HEALTHY 100

XX. THE MUSCLES, AND HOW WE USE THEM 105

XXI. HOW TO KEEP THE MUSCLES HEALTHY 109

XXII. HOW WE FEEL AND THINK 115