CONSERVATION 



CHAPTER XLVII 



THE EARTH FOR MANKIND 



Questions. 1. Does the earth support all the life that is possible on 

 it ? 2. How could the total amount of Hfe be increased ? 3. Would it be 

 desirable to increase the total amount of life ? 4. Would it be desirable 

 to increase the total amount of human life ? 5. Would it be desirable to 

 exterminate any form of life ? What would be the effect of changing the 

 balance of nature? 



6. Why cannot every individual plant or animal that is born reach 

 maturity ? What would happen if they did ? 7. How does each species 

 of animal and plant come to fit so well into its particular surroundings ? 

 8. Can an animal do as well in new surroundings as it can in its natural 

 environment ? 9. Is there really room for all the people who are born ? 

 10. Should not a nation try to make itself independent of others for all 

 its needs? 



384. Interdependence of life forms. All living things must 

 have food and water and air and a foothold. Since they all 

 depend upon the same sources of supply, there must be a limit 

 to the number of organisms that a given area can support ; and 

 that means that somewhere there must be a limit to the total 

 amount of life which the whole earth can support. In a pond, 

 for example, some of the plant life consists of algae and of larger 

 plants that bear seeds. These chlorophyl-bearing plants con- 

 dense sunlight ; that is, by means of sunlight energy they con- 

 vert carbon (from carbon dioxid) and hydrogen and oxygen into 

 carbohydrates, which are the basis for the energy of all proto- 

 plasmic activity. The protozoa and microscopic worms and 

 crustaceans live upon one another ; the fish and mussels and 

 larger crustaceans and worms live upon the smaller animals. 



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