Despite his short life and a professional career of only about twelve years, Swammerdam of Amsterdam was one of the outstanding comparative anatomists of the seventeenth century. He was a pioneer in microscopic studies, investigating especially the anatomy of insects. The present work, a classic on respiration, was his inaugural dissertation at the University of Leipzig and one of only four works published during his lifetime. He first showed that the lungs of a newborn infant would float if the child had ever breathed, and this discovery was put to legal use in cases of infanticide. The engraved title page illustrates his ingenious, if complicated, device for the study of respiration.