UNIVERSITY OF CAMBRIDGE DEPARTMENT OF PHYSICS
Medical Research Council Unit

‘TELEPHONE: CAVENDISH LABORATORY
CamMBRIDGE 54481 FREE SCHOOL LANE
CAMBRIDGE

6th December, 1956

Professor J. Lederberg,
Dept. of Genetics,
University of Wisconsin,
Madison,

Wis.

U.S.A,

Dear Josh,

I gather you'll be over next year for Ponte's meeting
and a Ciba meeting, and we're hoping that you and Esther will be
able to fit in a visit to Cambridge. There are many people here
who would like to see you, and of course we'd be only too happy
to put you up. Have you any idea when you might be here?

Ive just been on a visit to Edinburgh. Avrion Mitchison
asked me to mention that they'd also like you to visit them if
you can manage it.

Nothing exciting here except that our biochemist, Vernon
Ingram, has gone a long way to establishing an amino acid difference
between normal and sickle-cell haemoglobin, which, if confirmed,
will be the first case of a mendelian gene altering an amino-acid
sequence in &@ protein. There was a brief account recently in
Nature. Sydney Brenner arrives at the end of this month, and we
have plans to try a similar sort of thing in phage. ,

ret With best wishes to you both,

batt “y Yours ever,

x

F, H. C. Crick