CONTENTS 
I The World of Invisible Life II 
What is a microscope? What can be seen through 
a microscope? Where are living things found? 
How can we see invisible things? How can we 
grow them for ourselves? How can microbes be 
studied? 
II The Microbe 18 
What is a microbe? Are there microbes we 
cannot see? How can microbes move about? 
How do they grow? Why don’t they overrun the 
world? What do microbes live on? Where do 
they live? What does temperature do to them? 
What can destroy them? 
III The Microbes in Air and Water 28 
Are there microbes everywhere? Are they harm¬ 
ful to us? Does sunlight affect them? Can they 
live in water? What water is purest? Do 
microbes cause disease? Are all water microbes 
harmful? Is frozen water safe? 
IV The Useful Microbes 37 
What microbes are useful? What is yeast? What 
dangerous microbes get into milk ? How can they 
be killed? How do microbes help to make butter? 
How do they help to make cheese? What is 
mold? Where do molds grow? How do they 
multiply? Why is vinegar sour? Is yeast alive? 
What does yeast do? Are there bad yeasts? Are 
there microbes in soil? What have microbes to 
do with decay? 
V The Microbes that Make Us Sick 63 
What microbes cause sickness? What can prevent 
them? How do they enter our bodies? How 
long do they live? Do they affect all people the 
i 
