64 GENERAL SCIENCE 



6. How may the presence of disease germs in any sample of water be 

 determined? 



7. Why are such vigorous campaigns waged to exterminate flies and 

 mosquitoes? 



8. Why is it that the "scale" forming on the inside of boilers is so seriously 

 objectionable? 



9. Of what service is water in the nutrition of the body? Discuss how it is 



that the abundant use of water internally contributes to health and 

 length of life. 



10. In a general way what duties and responsibilities rest upon every in- 

 dividual in any community as to matters of public health? 



11. In what perfectly honest way may it be possible for a dealer in food- 

 stuffs to be able to sell at lower prices than some of his competitors? 

 Name some dishonest forms of competition in the preparation and sale 

 of foodstuffs. 



LIFE, GROWTH, REST, AND RECREATION 



Under the microscope it is found that both plant and 

 animal tissues are made up of cells. While there is a wide 

 variation among cells in form and arrangement, and in other 

 respects, every living cell consists essentially of a more or 

 less fluid content known as protoplasm. This possesses life, 

 and it has the powers of growth and of subdivision. Food 

 for plants and animals includes all the material required to 

 build new cell walls, to nourish the protoplasm, and to 

 furnish the energy required in keeping the organs of the body 

 active. 



The outer portions of the hair, skin, and nails, as well as 

 those growths known as corns, warts, and callouses, consist 

 largely of layers of dead cells. These are pushed outward 

 and away from the living growing tissues underneath. A 

 lessened blood supply to any such part of the body where 

 unnatural cell growth is taking place may hinder and in time 

 stop the undesirable growth. 



In trees the greater part of the wood structure consists of 

 cells largely or wholly destitute of life. So long as these are 

 enveloped by living tissue, however, decay of the wood does 



