Jr, SS

September 1, 1956

Dr. D. G. Catcheside
Bixwkugghem The University

Birmingham, Eng.

My deur Catcheside:

The Wine Festschrift has just come to hand, and I noticed there
your comment about "plasmid". I am afraidbthat all of genetics in in
for hard times remkamkta ternindlogically: aside from sjuabbles about
neodlogia, I an yuite startled to see how old standby's like "gene"
and "allelic" are being reshaped. What is there to do about it? I
ean think of few things more profitless than arguing about the aopropriate-
ness cf a usage, and we have neither the standards nor the judiciary
to asgess correctness; the only sclution I can see is to prefix a glossary
to every discussion, until we have some means of measuring and congealing
the consensus. So I have no deepseated objection to your re-defihition
of plasmid, but I fear it will be necessary in further uses to specify
which definition is being applied. Ne may end up like the taxonomists,
writing plasmid (Catch., not syn, plasmid Leder. ).

1956 is no longer 1952, and some of the issues have evaporated, but
I hope I can explain why I wanted to add to the plethora (to which one
could recently add homeostat, Danielli '56 also). In this country, plasma-
geneg wa,8 popularized almost simultaneously by Spiegelman and by Sewall
Wright, with a usage that comes close to "plasmagenic plasmid"; i.e.,
a gene-pgoduct with self-replicative capacities. At that time, both
Spiegelman and Sonneborn believed they had evidence for such intermediaries
of gene action. Shortly thereafter, Lindegren inbroduced "cytogane" as
& neure-synonym. In my own discussions, where I used plasmugene in the
generic sense, my correspondents here felt it had acquired the connotation
of a gene-initiated particle (you mightask Sonneborn about thet). This
may well differ, say, from Darlington'ts intention.

Then, Darlington himself (Nature, 1944) distinguished plasmagene from
plastogane.

Finaily, the main pont of my article was to correlate all the species
cf extranuclear determinants, including even highly organized endosymbionts
which may have a life history and genetic complexity of their own. I don't
believe any of the other terms then current curried this sanse, or if it
did originally, other connotations had accreted, as they almost inevitably
do. That article was provoked by my impatience over the suabble whether
kappa, @.g., was a "plasmagene" or a'virus", which is a ridiculous semantic
obstacle to getting to work on these determinants.

I am not clear whether plasmid (GSatch.} is intended as 4 category of
plasmid (Led.); I gather not if ite is defined as a} "a characteristic
product of each gene liberated into the cytoplasm" , regardless of its
reproductive behavior. The term "ergid" comes to mind as having been
used this way, but I don't remember where, if surely at all.

To my mind, it is no great loss to have this evolutionury diwergenee
in meaning; there is no stopping it anyhow, and better to have it obvious
than subtle. Jf writersare impelled to consider, and make explicit, their
nomenclature it my be all to the good.
Have you iny news of arrangements for travel support? Our Australian
trip Bagkms will be June 1 - October 1, and probably cannot be fitted into
a visit to Britain. But I do have an invitation for the Ciba in late
March & would be delighted to extend the trip then if it made it possible
for Esther and fie to come over together.

In any caee, with best regards, .
Yours since ly,

a -
i af fas

- Joshua Lederberg