A student of evolution, Gulick was born in Hawaii of missionary parents, and becoming a missionary himself spent most of his life in the Islands. Time spent in Oregon-California, in New York and England and at Williams College provided scholastic contacts which developed a love of nature and especially of shells into a deep interest in evolution. These letters between him and George John Romanes deal largely with that subject. They were published in part in the biography written by his son Addison, Evolutionist and Missionary, John Thomas Gulick.

This collection is composed of carbon transcripts of the letters, the originals of which are in the Linnaean Society of London, but the copyrights for their publication are owned by the Chicago University press. A microfilm copy of the Academy's holdings is on file in the library of the American Philosophical Society at Philadelphia.