Referee's report by Julian Sorrell Huxley, on a paper 'Mutation effects of ultra-violet light in Drosophila' by K Mackenzie and Hermann Joseph Muller Sectional committee: Zoology Recommended for publication in Proceedings. It is an important paper. A comparison to a parallel series of x-ray experiments should be added. Contains extra question - 'Is there any information contained in the paper which likely to be of value to the enemy?' Referee replies no. [Published in Proceedings of the Royal Society B, 1940]. Endorsed on verso as received 22 July 1940. July 1940