20 
THE GARDEN OF THE WORLD 
What causes 
bread to mold? 
cold. They cannot spoil fruit and meat which 
are kept cold. The ice box is one of our best 
protections against harmful bacteria. 
It is interesting and very easy to grow a little 
crop of bread mold to study. Moisten a piece 
of bread with water, leave it exposed to the air 
for a short time, and then put it into a covered 
tumbler. Keep it covered and in a warm 
place. In a day or two, it will be covered with 
fluffy white stuff that looks like cotton. In 
another day there will be tiny black balls 
scattered over the fluff. If you break these, a 
fine black powder comes out and floats away. 
The white cottony material forms the roots 
and stems of the bread mold plant. The roots 
go all through the piece of bread to soak up food 
and moisture. (It cannot grow unless the 
bread is moist.) The black powder is made 
up of a great many spores. Spores are not 
seeds, but they take the place of seeds for some 
plants. They are so small as to be invisible, 
and the air is full of them. When a spore 
happens to alight on a good place to grow, it 
