Faulkner asks Ewart for advice on feathers for an experiment being conducted at the University of Chicago, namely the age at which the juvenile plumage on the brown leghorn is repaced by adult plumage.

Contains chiefly correspondence with the Bulletin of the Atomic Scientists, co-organisers of the conference with the University of Chicago, who requested that Waddington submit a paper.

Also contains correspondence between Waddington and Sol Tax of the Department of Anthropology at the University of Chicago, who chaired the Conference, and correspondence concerning the publication of the discussions as Volume 3 of Evolution After Darwin (University of Chicago Press, 1960).

Most of the files of correspondence contain original letters from correspondents, as well as manuscript or carbon copies of Waddington's responses.