An overview of biology for the middle grades, this concentrates on the correlations that exist between living things. The emphasis is on the shared needs of food, water and air for both plants and animals and the necessity for continuous reproduction if species are to survive. In describing the balance of nature, a clear and fine distinction is made -- that the constant battle for survival needs not be visible or loud to be desperate. This has a smoothly written, well unified text and the black and white photographs serve as imaginative suggestions of the scope of this subject.