At C.41: manuscript draft. At C.42: typescript draft with manuscript additions.
Manuscript and typescript draft.
At C.38: manuscript draft titled as above. At C.39: two typescript drafts found clipped together, both headed 'Ch.12'. One is also titled in pencil, 'Adjustment & Balance' [the former title, 'The Hybridity Optimum', is crossed out]. At C.40: manuscript draft titled 'Ch.14 Selection and Variability', attached to pages of a typescript draft (headed 'Ch.12') which appears to be an earlier part of the untitled draft in C.39.
A draft figure for Chapter 13 is at at the end of C.102.
At C.36: manuscript draft. At C.37: typescript draft with manuscript inserts.
Included at C.83 is a letter to Darlington from F.A.E. Crewe, 1938.
Manuscript draft and typescript draft.