What have 
microbes to 
do with decay? 
62 WORLD OF INVISIBLE LIFE 
culture has successfully overcome the existing 
difficulties. 
The work of taking the nitrogen from de¬ 
cayed materials and putting it back in the soil 
where it can be used by plants is done by two 
very different microbes. One kind does the 
first half of the job, and the second kind 
completes it. Only the first kind of microbe 
can start it, and the second kind can do its part 
only after the first is finished. It is a compli¬ 
cated job, but it is going on around us all the 
time. The next time you see some dead leaves 
rotting or a piece of food decaying on the 
ground, you will know what really is happen¬ 
ing. These microbes are at work changing 
them into the nitrogen which makes it possible 
for plants to grow in the earth. 
