Referee's Report by [John Burdon Sanderson] Haldane on a paper 'A contribution to the study of animal populations. The natural control of the Knapweed Gall fly' by G C Varley Paper reference code: B.9 for 1941 [previously B.161 for 1937, withdrawn and later resubmitted] Sectional Committee: Zoology Believes the paper should be read to the Royal Society 'in time of peace, but probably not in war-time'. Recommends the paper for publication in the Philosophical Transactions [of the Royal Society], subject to shortening and correction of mathematical errors. [Not published in Royal Society journals but in the Journal of Animal Ecology, vol. 16, number 2, pp. 139-187, 1947]. [May - June 1941]