ELEMENTS 01' GENERAL SCIENCE 



CHAPTER XXIX. THE UTILIZATION OF FOOD IN ANIMALS 336 



Questions for Discussion. Food a universal necessity. The pur- 

 pose of food. The human body a machine. Preparation of food 

 for absorption. Motions of the alimentary canal. Proper care of 

 the alimentary canal. Transportation of food to the cells. The . 

 heart and circulation. Digestion and exercise. Food and work. 

 Food and body temperature. Food and repair. Proper balance 

 of foods. Tea and coffee. Is alcohol a food ? Does alcohol make 

 the body warm ? Alcohol and efficiency. Alcohol and long life. 

 Alcohol and the nation. Alcohol and the food supply. 



CHAPTER XXX. HYGIENIC ASPECTS OF NUTRITION ... 356 



Questions for Discussion. Needed care pain a danger signal. 

 Thorough mastication. Heavy eating. Amount of food. Con- 

 taminated food. Food and tilth. Circulation and nutrition. 

 Breathing and nutrition. 



CHAPTER XXXI. REPRODUCTION IN PLANTS AND ANIMALS 863 



Questions for Discussion. The meaning of reproduction. Repro- 

 duction of the yeast plant. Reproduction of pond scum. Animals 

 and plants begin as one cell. The frog's egg. Development of the 

 egg. The tadpole. Reproduction in birds and mammals. Repro- 

 duction in seed plants ; the flower. The pistil. The stamen. The 

 embryo plant. The seedling. Vegetative reproduction. 



CHAPTER XXXII. THE STRUGGLE FOR EXISTENCE .... 374 



Questions for Discussion. The fight for life. Overproduction 

 among plants. Overproduction among animals. Not food enough 

 for all. Climatic dangers. Destruction by disease. The balance 

 of life. Types of disturbance of nature's balance of life. 



CHAPTER XXXIII. PARENT AND OFFSPRING 383 



Questions for Discussion. Individual differences. The nature of 

 variation. Hybrids. Natural and artificial selection. Changes in 

 environment. Results of natural selection. Artificial selection. 

 Progressive results of artificial selection. Artificially selected types 

 not easily maintained. Inheritance. Heredity and the future of 

 the race. Controlling human environment. 



INDEX 8y7 



