QUESTIONS 179 



noticeable differences examine a drop of each under the compound micros- 

 cope. What do you see? What has caused the difference? 



QUESTIONS 



1. What can you say of tlie importance and abundance of bacteria? 



2. What plant diseases are caused by bacteria? 



3. Tell of the character and occurrence of the slime moulds. 



4. Why do canned fruits and vegetables keep? Why do they occa- 

 sionally spoil? 



