December 18, 1956

Dear Luca:

Congratulations to Alba and yourself, and best wishes for you and all
your family!

I think our correspondence is intact; I have a long letter from you dated
Nov. 19 (from Parmay or rather on Parma stationery), and then your present
announcement of the 10th.

As to our book, I think we should complete one chapter at a time, and am
quite ready to wait as long as you need. I am rather tied up now writing a
review or monograph on Recombination (sensu lato) which has been long since
(1953) promised for Bact. Rev. The penalty for waiting so long is the immensity
of the subject, but I think it a worthwhilem project, even though it keeps
me almost of the the lab for perkaps 3 months.

In that connection, I have made a summary of Demerec' data that may interest
you for the perfection of your note on the statistical theory of transduction.
This is his total account, about 40 tables summarized here in one. This notation
makes it mich easier to follow, (and criticize) his argument. I think you
will see certain defects. The best-established sequence is supposedly:

cys B45cysBl18 try AS B2 C3 ODid0.
But the order --B2—C3 shasmmt depends on item 13, which is the comparison

8:72:23. Similarly ~-C3--Dl0 depnds entirely on item 10, 23:393:26 , which

hardly is strdng evidence against --D10--C3 '26:393:23] especially as the
values for 23, 26 come from reciprocal transductions, i.e., different cultures
and lys&aes! The whole case for correlated sequences deperds on these imt items.
Howeverm there can be little doubt of the fact of close linkage of the factors
for the different steps; some of Hartman's data actually has prima-facie
evidence for the overlapping of functional segments, which in turn could give
the most rational explanation for the persistence of the linkage altogether.

At any rate, I thought this would be a convenient summary for you.
There is also a 4-point experiment(s) which comes out:

cysBl2 + cysBl8 - try AS + try Dll - a: 20 ba
__ b+be:(3 bed: {7
x-~ complementary e+be+tabc: 515 b+tabedonor :2618
adtd+abd: (212)

cysB45 * cysBl8- tryB2 + try Dll - a: 14 ae: 1 ad +acd: 23
b+ab+donor: 680
x-~ complementary b+be : (3) bd:(1) bed: (38)
d+adtabd: (220)

These results are actually in excellent agreement with the indicated order.

I do hope you are polishing your transduction note. We are going to

California tompppow for a week or so. If Adriano is at La Jolla how, we hope
to see hin. Sincerely,