[1] As a member of the Rockefeller Institute for Medical Research, he was the organizer the 1947 Shelter Island Conference where the experimental validation of quantum electrodynamics was first presented.
[1] MacIness obtained his PhD on the topic of ion hydration of aqueous salt solutions, from the University of Illinois in 1911 under the direction of Edward Wight Washburn.
[1] Botanist Winthrop John Van Leuven Osterhout persuaded MacInnes to come to the Rockefeller Institute for Medical Research in New York City as an associate member in 1926.
[1][3] During World War II, MacInnes worked on chemical warfare as director of a research group at the Rockefeller Institute.
[2] After the war, he and Karl K. Darrow organized a series of conferences focused specifically on quantum electrodynamics (QED) bringing top priority physicists of the time.