May 7, 1962
I don't think I thanked you enough for one of the most enjoyable evenings I've had in a long time.  Your dinner was sensational even if they were stale macaroons.  Because your guests and Dan were so stimulating and the discussions were mostly political, I never did get a chance to talk science with you.  It wasn't until the next day that Jack Preiss told me at lunch that you and Guilio had recently submitted a very elegant paper on the distribution of rare bases in amino acid acceptor RNA.  I wish I could have talked to you about it, but I hope that you will be willing to send me a preprint of this paper.  Under separate cover I'm sending copies of the two papers which have been accepted in the Journal of Molecular Biology on our sequence studies.  I hope these could be made available to anyone else in the department that's interested.
There are also two questions which I wanted to ask you and forgot.  These are:  a) the relative affinity of the different homopolymers for polynucleotide phosphorylase, especially in comparison to RNA; and b) the affinity of arsenate relative to phosphate in the depolymerization.  Any papers or preprints you have relative to the arsenalysis reaction would be deeply appreciated.
Please give my best to Dan and again let me extend a very sincere invitation to you both to visit us if and when you decide to visit the West Coast.
With best regards.
Sincerely,
Paul Berg