464 BIOLOGY AND HUMAN LIFE 



7. Sometimes a single species may have qualities or materials that 

 are of use to us, and other properties or materials that are harmful. 



8. Animals that are harmless or injurious in one region may be use- 

 ful in another, and vice versa. 



9. Animals that are useful may become injurious through too great 

 increase in numbers. 



10. Animals that are useful may become useless through the devel- 

 opment of cheaper or better substitutes for what they yield us, or 

 through changes in our ways of living. 



11. Animals that are of no use may become useful through the discov- 

 ery of their qualities by scientific investigation or through the develop- 

 ment of new needs. 



12. Animals of value may be in danger of becoming extinct. 



13. Animals in one part of the world may come to be of value to 

 people in a different region. 



QUESTIONS 



1. What are the most important native (uncultivated) animals in 

 your region in relation to human health ? 



2. What are the most important uncultivated animals in relation to 

 our food supply ? 



3. What are the most important uncultivated animals in your region 

 in relation to our clothing or other material needs ? 



4. What are the most important cultivated animals of your region in 

 relation to human food? 



5. What are the most important cultivated animals in your region in 

 relation to clothing and other material needs ? 



6. What are the most important cultivated animals of your region 

 in relation to human health ? 



7. How do you measure the relative importance of different animals ? 



8. What parts of the different animals are used as food besides the 

 flesh (muscle) ? 



9. What useful animal products can be replaced by plant materials ? 

 by mineral materials or synthetic products ? 



10. What dangerous animals are there in your region ? What can be 

 done about them ? 



11. What useful animals in your region are dying out? What should 

 be done about them ? 



