218 INTRODUCTION TO BOTANY 
for them were attacked by these preventable diseases, the 
matter would not be so serious, for in that case disease and 
the resulting deaths would tend to eliminate those who do not 
act upon the knowledge of sanitation which we now possess ; 
but many innocent people suffer because others do not take 
proper precautions against the spread of diseases over which 
they might have control. As one means of protecting the 
public many states have laws preventing the use of public 
drinking cups. Attempts are made to have school children 
drink from running water, so as to make sure that all con- 
taminated water flows away. We need many more regulations 
of the same kind in order to guarantee a reasonable security 
against the needless spread of disease. 
PROBLEMS 
1. How can you show that the process of decay is of advantage to 
living things? Would decay take place without the action of dependent 
organisms ? 
2. What are the relative advantages and disadvantages of prevent- 
ing the decay of food by refrigeration and by the use of chemicals? 
Why are chemicals sometimes used where other means of preservation 
might be adopted ? 
3. What are the surest methods of preventing the spread of bacterial 
diseases of plants, such as pear blight and the black rot of cabbage? 
4. Would the fight against typhoid fever be won more quickly by 
destroying all flies that carry typhoid or by destroying all infecting 
material from persons who have typhoid? 
5. In your school and community what are the chief needs for a 
better understanding of the nature of bacterial diseases ? 
6. What are your local regulations in regard to quarantining persons 
ill with infectious diseases? in regard to preventing the introduction of 
diseased fruit trees? of diseased animals? 
7. What bulletins has your state agricultural experiment station or 
your state board of health published dealing with the relation of bac- 
teria to human disease, diseases of farm animals, dairying, household 
industries, or agriculture? 
