1651 East 21 Street
Brooklyn 10, New York
June 10, 1956

Dear Larry,

I calculate that by this time you ought to be finished with my experiment
and thus have time to read tuis letter.

I didn't attend many of the sessions at Cold S»ring Harbor although those
that I did attend were very good, Naturally, I was most interested in wnat
Jacob, Wollman, and Hayes (who were all present) had to say and just wrote a
two-page letter to Josh on that matter. Hayes apvarently had little to
contribute to the oaper but wanted to be recorded@ as one who snared the new
viewpoint. And that new viewpoint is, of course, unidirectional transfer and
prezygotic rurture (! with or without erotic induction) plus some borrowed
shavings from McClintock. F is evideatly a controlling element which usually
sits near TL;xm occasionally it jumps behind Gal (or elsewhere). Tais jump
is resnonsible for mutation of Fplus to Hfr.

Nevertheless they had a lot to say. I thought they had preity good evidence
that all cells in an Hfr culture mate, The argment is thus. for 10 HirsHay es
cells, with erotic induction operating, 50 infectious centers and 10 TLS
recombinants ere proauced, Without erotic induction, one gets 20 recombinants.
Henee, if lysis of the zygote results every time that lambda is tran:cerred to
the zygote, lambda enters the recipient cellf half as often as TL. But since
lambda enters 50% of the time, then TL enters 100% of the time. Wollman cleims
cytological corroLoration for this conclusion (that's for Bradley), but also
claims the same for Fplus cultures, Then Wollman concludes that the Frlus
cultures mist be trunsferring some character at Hfr rates, Therefore F is a
chromosomal character, the only character transmitted by Folus cultures at
Hfr rates, other characters being transmitted with low frequency.

Then, of course, I think they have conclusively d:monstrated that all #>lus
crossing is due to Hfr mutants. The fluctuation test4# may not be “he last word
in such matters but they have suaceeded in isolating Hfr mutants by indifrect
selection in three different cultures; it seems to be very re, eatable as even
Hayes can do it.

By the way, I ran into appleyard; he asked me what Esther was doing with
h lambda. (!) (!) (4) (tps)

Give my regards to the Tuesday night club-members. I'll keep you posted
on develo:ments at home when I get there.

Gluw