3 JANUARY 1969, Page 27

Elixir of youth

Sir: In a 'double-blind control experiment' (John Rowan Wilson, 27 December) it is not only the 'assessor who is ignorant as to which patient is which. The patients equally do not know if they receive the treatment or the placebo. Hence the word 'double.'

Leon M. Shirlaw 3 Parkway, Gidea Park, Romford, Essex