CONTENTS 



IX 



Out of the soil with 

 the aid of light comes 

 plant life, on which 

 animal life is ultimately 

 dependent. 



CHAPTER XIII. LIFE ON THE EARTH 



Plants Plant Roots Cells Stems Graft- 

 ing and Budding Leaves Flowers Seeds 

 and Germination Dependent Plants , 366 

 Needs of plants. Functions of parts. Leaves as 

 factories. Peculiar plants. Pollen. Bacteria, 

 molds, and rusts. 



Animals Invertebrates: Protozoa, Worms, 

 Insects Vertebrates : Man : Structure, 

 Breathing, Circulation, Senses, Sight, Sound, 

 and Hearing, Food and Digestion . .399 



Health hints. Adenoids. Deep breathiug. Work 

 of white corpuscles. 



The treatment of life 

 in the preceding chapter 

 leads to the study of 

 man's control of the 

 means of maintaining 

 We food. 



CHAPTER XIV. MAN'S EXISTENCE AS RE- 

 LATED TO PLANT AND ANIMAL LIFE 



Fundamental Foods Necessary Foods Bev- 

 erages Alcohol Tobacco Cooking of 

 Foods Bacteria Preservatives Infectious 

 and Contagious Diseases Antitoxins How 

 to Disinfect Dangers from Infected Food and 

 Water Pasteurization Sewage Disposal 

 Cleanliness Dangers from Mosquitoes, Rats, 

 Flies Health Hints . . . .425 



Carbohydrates, fats, proteins. Minerals, vita- 

 mins, relishes. Bacteria in bread, cheese, and 

 vinegar. Disinfection and sanitation. 



This chapter concerns 

 itself with man's con- 

 trol of his physical en- 

 vironment by means of 

 machines. 



CHAPTER XV. MAN'S INVENTIONS FOR 

 TRANSFERRING AND TRANSFORMING ENERGY 



Primitive Tools Friction The Lever 

 Wheel and Axle The Pulley The Inclined 

 Plane The Wedge The Screw Man's 

 Most Important Energy Transformers Con- 

 servation of Water-power . . . 459 



Work, energy, and power. Water-power, tur- 

 bines. Steam and gas engines. 



