Dr. Jonas E. Salk, who discovered the polio vaccine, reads with his wife and three boys in Ann Arbor, Mich., on April 11, 1955. The boys were among the first vaccinated during testing. The family was photographed the night before an announcement the vaccine was effective. Pictured from left are Jonathan, 5; Donna Salk; Peter, 11; Salk; and Darrell, 8. (AP)
