This series includes material relating to his career at the John Innes, its uneasy constitution, the move to Bayfordbury, and the problems of the organization of a research establishment highlighted by Darlington's departure for Oxford. There are annual reports and minutes, liberally annotated, going back to the earliest days of the Institution in 1910.

Darlington spent over thirty years at the Institution, entering as a 'volunteer unpaid worker' in 1923 under Bateson's directorship, becoming in 1937 Head of the Cytology Department and, on the retirement of A.D. Hall in 1939, director. He resigned in 1953 on his appointment as Sherardian Professor of Botany at Oxford. It was at the Institution that much of his crucial work on cytology and chromosome theory was carried out and that many of his deepest professional contacts were made; these included W.C.F. Newton, J.B.S. Haldane, A.D. Hall and others on the staff, and a series of distinguished British and foreign, including Russian, visitors (see Memoir, pp.118-119).

When Darlington became director, the Institution still occupied its original site at Merton (London) and suffered bomb damage as well as loss of charitable income during the Second World War. Some of the efforts to find a new site are documented at, e.g., MS. Darlington c. 10/B.26-29 & 34, MS. Darlington c. 11/B.37. Eventually the Institution moved to Bayfordbury, near Hertford, in 1949. Its next move, in 1967, was part of a major re-organization which incorporated some of its departments into the University of East Anglia at Norwich.

The administration of the Institution in Darlington's time was uneasy and the director's position in many ways anomalous. The council included the trustees of the John Innes Charity, and representatives of government, the universities and horticultural and farming interests. The director attended council meetings by invitation to present his reports but was not a member of it and saw its minutes by courtesy, not of right. For a temperament as impatient of authority as Darlington's, this was particularly irksome; with other colleagues he made representations to council for a change in conditions in 1936 (MS. Darlington c. 10/B.19-21) and wrote several memoranda at and after his resignation (MS. Darlington c. 11/B.48, MS. Darlington c. 12/B.52-54) as well as incorporating his views into various historical accounts (MS. Darlington c. 11/B.49-50) to which he continued to add to the end of his life (see especially MS. Darlington c. 13/B.78). The move to Norwich and the link with East Anglia also aroused his displeasure and his campaigning zeal (MS. Darlington c. 12/B.55-73). The annual reports and minutes (MS. Darlington c. 13/B.80-85, 89-92; MSS. Darlington d. 4-6) are of interest for the underscorings and background comments, contemporary and retrospective, which Darlington freely bestowed on them.

Material relating to this long and important stage in Darlington's career is also to be found elsewhere in the collection: his own research and the history of science and scientists in Section D, expeditions, visits and conferences in Section H, correspondence with colleagues in Section J. There are abundant references to the Institution and its personnel in the autobiographical writings, diaries and jotters in Section A.

The title 'John Innes Horticultural Institution' has been adopted as the heading for this Section, as being the original name and that operating throughout the period of Darlington's active connection with the place. The official name was changed to 'John Innes Institute' from 1960; in practice, written and spoken usage was '(the) John Innes' and this shortened form is used in the catalogue entries.