Dear Dr. Curtiss,
Many thanks for your very thoughtful and informative memorandum.  I have read it and reread it carefully and each time new information or a new idea emerges.  I can't say that I agree with most of your proposed remedies or even your definitions of experiments that should be considered (for example, I could think of virtually no experiment that could escape the definition suggested for Type 3 or Type 4 experiments).  Is that intentional? But because you do know a great deal about plasmids, we are all obliged to bar your views and arguments and I do hope that we can get you to come to the meeting to be held February 23-27, 1975, at Asilomar (Pacific Grove, California) where these matters will be discussed and hopefully some proposal acted upon.
In the meantime, I was very much interested in references to some of the points you made.  Is there a good source(s) for information summarized on p. 3-4 (Functional Attributes of Plasmids) and on p. 6 (Virulence of E. coli); I was also interested in the references for the last two sentences in the first paragraph of p. 5, that is, that plasmids in Streptomyces code for the enzymes which synthesize antibiotics.
In closing let me thank you deeply for your response to our proposal. I know only too well the difficulty in deferring an experiment one has worked hard to get to when the reasons for doing so are still only problematic.  I hope we can remain in touch.
Sincerely yours,