P.S. Schmid & Kauffmann mention having received three 3. paratyphi 4, O-forms from
you. I had go idea you had these. Sometime would you send then? No hurry.

J.
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Dear TrhALL:

Yours of the 4th just received. I was hoping you would tear into the ms.
It should be made as clear as possible, and my past performance in this direction
has not baen (to say the least) consistently exemplary.

It would obviou ly be a good deal easier for us to go over this thing in
person. But I will not implore you again (won't I though!) to consdder a brief
detour to Madison, during your coming trip.

I will wait to hear your detailed remarks before discussing the ms. further.
But I will try to answer some questions of fact. SW-959 seems to be my oversight,
and of course has to be documented. It is your Hines V.A.H.

I do not think further absorptions are indicated now; the point is already
adeyuately made.

You mention SW-986 as being diphasic. Does this mean you have separated cut
pure i ami pure enx reacting colonies?

I pprposely tried to leave out any detailed thedretical discussion, because
I do not feel that any comprehensive theory of phase variation has yet been sub-
atahtdadted. I would have no objection to repeating in the discussion that diphasic
types have been found in transductions to certain moncphasics, ae already stated
on p. 13 and in table 2, There is no thepretical contradiction from this finding.

The back-biting behavior of the phage released from S. typhimurium LT-7 is
perpl to us too. There have been a few cases like it in the litarzture
but none (including this one) have been carefully worked out. I would assume
that LT~7 typically carries a phage which could probably be tested for easily
enough on other indicators, but that only a rare particle has “mitated" so as
to be able to attack the strain of origin. ‘reatment with penicillin induces the
release of enough of the mutamt phage that there will be an appreciable likelihood
for the occurrence of one of these mitant particles, which is then abies to grow
at the expense of the parent bacteria. There is something rather like this in
K-12 (p. 58 of our Genetics, 1953 paper), but the lambda~2 mmtation occurs mich
less frequently. Although I would assume that the mm typical phage released
by LT-7 could be used for transduction if grown on a suitabla indicator, we have
in fact worked only with PLT~7' (the back-biting mutant phage) which can be grown
either on LT~2 or on LT~7. Phage very defihitely will transduce to bacteria which
it will not lyse (e.g. PLT-22 on LA~22), but we have generally had other indicator
strains to measure the phage by plaque formation. Without such strains, we probably
could not grow the phage to sufficient tiber, though we could perhaps use ultra-
viclet induction of lysis of lysogenic bacteria (Lwoff effect).

The lw situation would be nice to work out. Unfortunately the unijue strains

ef S. darees-salaam and 5S, wien, which are about all there is to work with in