Washoe County Library System

Though most of them are too small to be seen with the naked eye, bacteria are everywhere. They appeared on Earth more than 3 billion years before the first dinosaurs. Some bacteria cause deadly diseases, but many of them are helpful to us. They fertilize the soil by breaking down dead material, and they are an essential ingredient in many foods. Bacteria in our own bodies are a vital part of the digestive process.--from page 2 of cover.