LIST OF ILLUSTRATIONS 
When Spring unlocks the flowers to paint the laughing 
soil ( frontispiece ) 
Interesting things may be seen through the microscope 13 
Types of microbes 19 
Mountain air is nearly free of microbes 29 
A river in a city is usually filled with germs 33 
Mil\ is made up of drops of fat 39 
Fresh mil\ contains many useful microbes 43 
Mold is a small plant 49 
Apple juice with the help of microbes ma\es vinegar 52 
Without the help of microbes, bread would not rise 56 
Clover plants enrich the soil with nitrogen 60 
Scratches from pets may cause serious illness 66 
Some microbes are harmful and cause sickness 70 
Microbes are spread through a public drinking cup 71 
Certain microbes help in churning butter 73 
The horse helps man cure scarlet fever 82 
Primitive peoples thought mas\s cured leprosy 89 
A maple leaf 96 
The potato is a root which contains starch 103 
A pea pod 105 
Pollen as seen through the microscope 107 
Microbes are useful in causing decay 112 
