This correspondence is with Charles Francis Adams, Jr., Edgar Fahs Smith, and Thomas Sovereign Gates, about undergraduate days at Harvard College, his interest in Harvard, the University of Pennsylvania, and the Wistar Institute. The papers include a list of publications, biographical data, papers on Robert G. LeConte and Daniel Moreau Barringer, a certificate of membership in the Governor Thomas Dudley Family Association, and 25 drawings of crystals and 35 original sketches made to accompany his Harvard thesis, "The Nature and Origin of Deposits of Phosphate of Lime."

This collection of Morton letters forms part of a bound volume of incoming correspondence. It is a companion volume to the original letters in the Morton collection at the American Philosophical Society, which were also originally bound. Most of the subjects of the two collections overlap, but additional subjects in the microfilmed collection include American Indians, archaeology, Egyptology, and phrenology.

This is primarily a collection of letters, with some additional documents, concerning Young's interest in botany, geology, mineralogy, and natural history. There is information about Bowdoin College, where he studied under Parker Cleaveland. There is also much on the natural history of Maine, where he was the State Botanist in 1847-1849, and also on the Bangor Natural History Society. There are materials on Brazil in relation to Young's service there as the U.S. consul to Rio Grande do Sul from 1863 to 1873. There are also letters from his brother, John C. Young, and his sister, Sarah Augusta Young.