We all breathe. All people and animals draw air into their lungs and then puff it out again. In the air we breathe are molecules of oxygen. Our bodies use this oxygen in the process of living. So, if all the living animals are using oxygen every minute, why isn’t the oxygen in the air used up?

Everything we eat comes from plants. Why don’t the plants get used up too? What are they using to grow and to make new seeds?

Three centuries ago, a Belgian scientist, van Helmont, and later a British experimenter, Stephen Hales, asked themselves these questions. They found that there were different gasses in air. Other curious and brilliant scientists, whose stories are in this book, figured out how we exhale carbon dioxide, and how plants use this gas to make more oxygen.

In this century, suddenly, we find that we need the green growing plants on our earth to survive. Here is the tale of the step-by-step discoveries that may save our lives and our planet.

Adult Asimov readers would be better off going to Photosynthesis for a discussion of this topic, but the illustrations are quite nice and except for an unusually rocky first chapter, this is a good treatment for younger readers.