From Mabel Taylor
Catherine de Lange describes work on biological clocks (16 April, p 30). But some of the findings she reports have long been known, as shown in Gay Gaer Luce's well-researched book Body Time (reviewed in New Scientist, 6 November 1972, p 417). It is amazing how such ideas can come back as mainstream 40 years later.
Knutsford, Cheshire, UK
