243 
or the way in which they live. Every plant which has green 
coloring matter (chlorophyll) is able to make its food from the 
simple materials which are present in the air and in the water 
of the soil. Those living organisms which are destitute of green 
coloring matter are unable to make their own food and are there- 
fore dependent upon other organisms for their food supply. The 
Fig. 34. The fruit of a fungus on an oak stump. 
bacteria belong to this latter class and there are two ways in 
which they may obtain their nourishment: (1) They may prey 
upon other living animals or plants when they are said to be 
parasites or (2) they may live upon decaying matter when they 
are known as saprophytes. 
