This biography describes Humphry Marshall's involvement in the international exchange of American plants between 1750 and 1800, with illustrations.

Letters collected by Whitfield J. Bell, Jr., including correspondence and papers submitted to the Society. Pertains to APS members and associations. Includes letters by Franklin, Winthrop, Endecott, Eliot, etc. Scientific and historical references, primarily. Some of the subjects discussed are astronomy, botany, electricity, natural history, and Indian missions. Also included is Roger Curtis' "Journal of the Moravian Mission to Labrador."

These letters relate principally to provincial business and comment on the Indians of Pennsylvania, the French and Indian War, a survey of the Maryland-Pennsylvania boundary, and the Stamp Act. Correspondents include James Burd, Jeremiah Dixon, Joseph Galloway, Humphry Marshall, Charles Mason, Edward Shippen of Lancaster, and Edward Shippen, Jr.