Thank you for letting me see the enclosed letter (I have a copy for my own files). Without referring explicitly to my having
seen it, I suppose you would not object to my stating that I had heard its substance from you. I don't see how I can
initiate any discussion with Plough myself. I have repeatedly sent him abstracts, copies of progress reports, and once a
brief personal note, but have had no reply. It is obvious he was thoroughly preoccupied in Washington and had undue confidence
in his assistants.
As you observed, there is no longer any essential difference in our findings. He may still have an interesting story with
his odd triple mutant, but we will have to wait to see how that settles out. Like him, I have a priori objections to the
idea of unit factor transduction, and still prefer the notion that small fragments of chromosomes are involved. These fragments
need not correspond to single genes in any sense, except that we do not ordinarily have more than one detectable factor in
Lately, that triple-aromatic mutant (LA-22) has been giving some few spontaneous reversions to prototrophy, and I think Norton
must be having a similar experience, although we did not get them earlier. This would imply that a single genetic change
can lead to prototrophy, whether or not these reversals prove to be back mutations or suppressors. As the source of FA is
a difficult strain, LT-2, from LA-22, this may be all that's needed to justify the previous conclusion that LA-22 is indeed
a two-step, single-factor mutant.