5th Deoember, 1962.

Dr. S. Oohoa,

Department of BioohemPstry, '         *

New York University Sohool of Bbedioine,
550,Firat Avenue#
New York 16, KY., UJ3.A.

Dear Severe,

    !Fhank you 80 much for the letter and the preprint. I
must really congratulate you on the poly A-polylysine result.
We are all kloklng ourselves for having timed 2-L Nstumlly
I am delighted that you are finding more triplets. You will
remember that when I vi&ted you lagit February I felt sure
that there would be many more than the ones you had then. I am
still not very happy about the ldentifioation of triplets, and
feel that it fe important to make polynucleotides raith a ran-
of oompositfons and not just 5~1 or lt5*         .,

    As to the question of degeneracy I feel that if all the
oodons are tri@lett;a, and if, cay AUC, ACC, AGC and LI$'--8 all stand
for hfstid1ne (we would write this as A*C) nevertheless one
would oall this degeneracy,  You wfll dee that I dierouss such
possdbilltiee Pn my review*
RNA (see pages 62 and 63)*  inoluding your point about transfer
                    On the other hand 3f RoberWs oode
were correct, icer a mixture of doublets and triplets, one for
eaoh amino acid, so that the reading sometimes moved on two
step@ and eometlmes three, then I would agree that it should be
called non-degenerate,  However, I feel our genetio results
make auah a code unlikely. X w9sh 1 could penetrate the loglo
(if any) of the degenerauy but 80 far it has baffled me*

    Off to Stockholm in a day or 80,  It will be quite a
family affair this Wme,

  With all good wishes,
                                                                             .

                     

F. H. CL Crick