54 GARDEN PROJECT 
tropics? Such a climate generally makes men indolent 
and lazy. 
In the temperate zones, however, the earth produces 
food only a portion of the year. During the remainder 
of the year, man must live upon food which he has 
preserved or stored. One of the great advances in 
civilization was made when man domesticated some of 
the wild animals and could thus preserve food in the 
live state. Animal food may be preserved this way 
but other methods are necessary for the preservation 
of food plants during the winter months. 
Why foods spoil. Why are special measures neces- 
sary to. preserve foods? What makes them spoil? 
There are three families of plants which grow in living 
or dead material, in about the same way that other 
plants grow in the soil. These are yeasts, molds and, 
bacteria. You are familiar with members of all three 
of these families. Yeast is used in making bread. Per- 
haps you did not know that it was a plant and that 
its growth is what makes bread rise. Mold you will 
recognize as the grayish, cob-web material you find on 
bread if kept in a warm, moist place. Bacteria makes 
you think of diseases. Perhaps some of you have 
had the opportunity to look through a microscope at 
some wriggling, squirming objects which were called 
bacteria. 
Bacteria like people. Bacteria are like people; they 
may be either good or bad. Were it not for bacteria 
the clover plant could not get its nitrogen from the 
air. What finer example of neighborliness do we have 
than the clover plant and the tiny ‘‘bacteria’’ plants 
living together, one helping the other? Perhaps you 
did not know that all plants with which we are familiar 
are dependent upon bacteria for food. When a farmer 
