3 May 1957

Dr J. Lederberg,

Genetics Department,

University of Wisconsin,

Madison, Wis. Ref. Skaar et al., PNAS 43:329.

Dear Joshua,

Since I don't know Skaar, I cannot vrotest to him as
vehemently as I can to you that I don't like "motilizction".
I don't like "chemostzt" either, and "substrains" and other
argot, but it's probably too late to do anything about them
now. (Provasoli refers to contaminated algae as "bacterized",
which I find equally offensive. )

More seriously, why risk explosions (footnote 4)?
I should have thought that the spreading of colonies on
0.4% agar in plates would provide a suiteble device for
the selection of more motile strains; or why not vut a
glob of bacterized agar at the bottom of a tube, fill up
with 0.4% agar, and race the organisms to the surfrce?

I lost myself on footnote 3 (p.332, line 3), which
sounded interesting.

Can F have anything to do with the filaments which
Maccacaro & Angelotti discuss in Giorn. di Microbiol. 1:85-96,
1956? I often wondered what they are doing.

Could you not select for F+ to F- mutations by a
replica plating method? Grow up a few hundred F+aB, stamo
out on a complete plate, and then on a minimal vlate svoread
evenly with F-Ab. Provided you get enough metings, there
should be a smudgy colony for every original F+aB, whereas
mutants to F-aB would be represented on the complete »vlate
only. I suppose you could re-replicate from the mixed
plate to some suitable phage plate if you are worried by
syntrophy problems. (I hope you can get meting on
agar. I know you used not to in the vrimaeval days, but
things seem to change so rapidly.)

I'm sure the climate in California is much nicer
than that of Wisconsin.

Best wishes to Esther.

Yours,