Editor,—Harding and van Heyningen1have done me the honour not only of testing a tentative hypothesis relating to a possible link between the season of birth and the prevalence of [one type of] cataract, but also of quoting from a preprint I sent them. The latter showed that a statistically significant variation of the season of birth is to be observed in the prevalence of mixed nuclear and posterior subcapsular cataracts both in an immigrant Indian population and among natives of the British Isles.

The latter observation does not seem to have caught the authors’ eyes, and I made no claim for the conditions described in their paper. While my results may not be valid for …