October 1, 1956

Dr. F. Kellenberger
Geneva

Dear Dr. Kellenber ger:

Thank you for your letter of September 27, and for the reprints on L-forms
recently received. I was, of course, unaware of this work until now and have
been pleased to see it. The main advantage of calling the Qlobular forms
"p-otoplasts” may be as a basis of persuading Spiegelman and others to shift
to this mterial for the physiological studies theyg had been doing before
with B, megaterium, I am concerned to call more explicit attention to the
rich literature on L-forms, and their relationships to my "protoplasts" which
may npt have been sufficiently emphastied. I have therefore submitted the
enclosed note as a sort of postscript to the ms. you alreedy have.

Recehtly we have been learning to produce and grow the L-forms of F. cold
K-12. There is a great deal of individual strain specificity, and finigkiness
about media, in this and we still don't have a thorough picture. Our cbjectives
are those already indicated in the first ms.; in general, the genetic properties
of the L-forms (and, if they occur, the genetic basis of the irreversible L form.)

Your remarks about your student's work on Gal transduction are somewhat puzzling,
and I will defer comment until we have studied them further. Are you dealing with
transductions within the K~12 line? (My wife had noticed some deviations in the
behavior of transductions among different E. coli strains). We have never observed
"stable immunes" coming out of transductions to Ly® recipients. However. an

Lp-"immune" heterogenote (hypothetically designated as: Gal- Lp® ex/ Gal~ Lp’)

can give rise, in addition to Gal+ and Gal” haploid, Lp® ; segregyants to another
class which (in the sams notation Gal- Lp® ex/ Gal7 Lp®) is now pure for Gal~ and

still immune, but actually homogenotic for Gal, and unstable for the immne charac-
ter. I.u., the immune Gal7 invariablg segregate sensitive Gal™, and also meet other
tests for being homogenétic for Gal (e.g., reversion followed by segrem tion). Does
this contradict your findings?

We have some problem of comaunication here, is Dr. Morse has now moved to
the Dept. Biophysics, Univ. Colorado Med. Ctr., Denver 20, Colorado. It would be very
helpful af you could send another copy of your informative correspondence to him
for his comment, which would be easier than if I have to copy your letters.

Yours sincerely,
/

i

. i |
Wdoshuad Lederberg -
v Professor of Geretice