BACTERIA 235 



6. In preserving food from decay, what advantage is taken of the fact 

 that plants need moisture for growth? 



7. In canning foods, why is it necessary to bring the materials to a 

 high temperature? 



8. Why is it customary to seal the cans containing such food? 



9. Canned foods may be preserved from decay if, while still hot, the 

 jars containing them are closed with a wad of cotton. Explain. 



10. In preserving foods from decay, what advantage is taken of the 

 fact that plants need warmth for growth? 



11. Why do canned foods soon spoil if exposed to the air? 



12. Why are damp rooms undesirable as residences? 



13. Why are cellars and other poorly lighted places undesirable for 

 residences? 



14. Of what use is it to expose bedding to the sunlight? 



15. Why is it desirable to avoid contact or association with persons 

 who are suffering with disease? 



16. Why are manufacturers forbidden to use certain kinds of chemicals 

 for preserving foods? 



17. Make a list of the antitoxins of which you have heard. 



18. Make a list of the disinfectants with which you are familiar and 

 check those which may be used as antiseptics. 



