September 24, 1956

Dear Norton:
How go the protoplasts?

Since coming back to the lab after a sumer trip, and breaking in a couple
of student-assistants, I have minly been busy with two things: learning how
to grow L forms of E. coli, ami counting how many papers have already been
published on the formation of protoplasés with penicillin. Both tasks have
been messy: the lot of agar seems to be critical for the first question; as
of today we've settled on a batch of New Zealand ager which seems far ani
anay the best subéérate for L colonies of K-12. Yes, though the p. only enlarge
and de not proliferate id broth, they give rise to L colonies ia tim (not on)
the right agar. I don't yet have passage strains of the K-12 L, much less any
experiments on thatr genetic properties, which is the point of the whole business.
No more luck than that yet either on DNA effecta, but I've been hopeful that
the L (1.¢., protoplastic) colony will be more susceptible.

The part of this story that has provoked the most discussion has been the
mechanism of penioillin action. I thought it was adequately covered in one
sentence in the 7PMAS note, but evidently not, judging from the explanations
that have been called for. I'm not surel'd bother with this at that, except
possibly for the nonsense that Gale has promulgated. Anyhow, I thought you'd
be curious to see this. If ‘ve seen a comparable formulation anywhere else,
at least Quikex closer than per's, I hope youell let m know.

Have you tallied to Dean Fraser within the last couple of months? What is
versens doing in this story?

Yrs. sincerely,

ys, Joshua Lederberg
ft - 4

. a

;

P.S. I hear Tatum's coming to Rockefeller! “ow.