Dramatizations of the significant discoveries of twelve scientists, among them- Leeuwenhoek, Jenner, Koch, Pasteur, and Salk - highlight the challenges inherent in the conquest of disease. Simply written, these episodes are interrelated so that the reader can comprehend the dependence of each scientist on the work of others before and after him. Were it not for Leeuwenhoek's observation of tiny animals in the lens of his microscope, Jenner might never have developed the smallpox vaccine... Were it not for the unknown country doctor named Koch who grew anthrax germs, Pasteur might never have found a cure for this dread cattle disease... In modern times, Enders' basic research paved the way for Salk's momentous achievement. Fourth and fifth graders can easily absorb the information given as well as the vital aspects of interdependence that made these discoveries possible.