This is the fourth title in an introductory series in which each book deals with some aspect of the human body. The previous books have covered blood, glands and the nervous system. The structure of the nose, throat and lungs is clearly described and illustrated in labeled and captioned cross sections. The lung action in breathing as well as the supply of oxygen to the blood stream is explained in words and pictures that should not be beyond the easy grasp of fifth and sixth grade students. The effect on the body of ""thin air"" at great heights is one of the more complex factors in respiration given a chapter to itself. A glossary of the unfamiliar terms and an index are provided.