June 24, 1956
Synday

“ Hi Larry:

We just got back from Baltimore (by train) a few hours agoy I had not
quite completed a lonzhand letter, but you wouldn't ve able to read my
calligraphy anyhow, so it's been done over. Esther's gone over the first
part of the conference, :

Altogether, it was no 7 day wonder, Jacob has a phenonenally detailed
story om prophase eenetics as well as sexpality, which I'm inclined to
beli¢ve except for details; we have te thrash these out at Ann Arbor, where
we hope te have more time together, I was pleased that we could zet together
in such a cordial mpet spirit, afnd am gping to do my best to keep it that
way, What I could clean so far is that be's worked with 14 phages, of which
7 are inducible and Gal~linked; the other 7 are noninduseible and in the Mal=Xyl
region, rather resembling Pl, They've more or less stayed miiix away from trans-
duction work, except of prophages. The 7 inducible phages have distinct lyso-
genic sites 4n K-12, but can be crossed to one another. They are also distinct
in ergss-immnity, The phage-determinant for site of fixation seems to be at
the seme (phage) locus as determines irmmity reaction, and the same as a locus
for clear-plaque mtation which determines ability (49 lainbda)to lysogenize at
ally. Jacob does most of his mapning in terms of "time of penetration" in
interrupted fertilization experiments,

Herriett Fbgrussi and Rollin both talked about quantitative titration of
DNA per --x (after ahowt 20 minutes each of what Jacob called tjokes' and*thow
to shake a tube'), with kinetics that was quite inconsistent, and useless in
elther case, Bven with loglog plats they get, respectively:

a -

but when T asked the innocent question of how many DNA molecules per cell
and per ~—x, the anewer was "but of course you can't anewer that becanse the
tine during which cells remain competent ia limited, and the DNA's interfere,
etc, etc." And in any case, they could not demonstrate that the supernates ‘ose
any activity. BO what ere they measuring? Fran this I would conclude that radiation
kineties, fractionation work, ete are an absolute waste of time Though Bendich
clains to have had sane partial separation of different activities}, Could you
gently outz Lerman abet this, or at least watn hin, .

The Henophilus system may prove cleaner, not Zemenhoi''s work which 4s inpessib]
unquantitetive, but Goodgal and Herriott who are really digging in. It is fantas-
tic that these studies still haven't reached the level of an acceptadle M.S. thesis

We had 2 satisfactory tote-atete with Kalckar and Kurahashi, but he still
le$ same af the catfur out of the bag, After Hartman misquoted the ms, about
the PE relations of 1,4,7 and 2, I had to sey that the former Delgad to the
sane "cistron" (a possibly useful Benszerian tor Pa group) but that wpe we stead~
fastly refuse to draw any conclusions so far. (dartman's om talx as Esther
mentions was simply awful; I never thought transduction could be made dull!)