October 15, 1950.
Dear Doctor Dianzini:
Your paper in Experimentia, "Mutation in the enzymatic equipment of Escherichia coli and Proteus OX19 directed by desoxyribonucleic acid isolated from bacteria of the same and of different species", has just come to my attention.  Would you be kind enough to favor me with a reprint of this paper, and to keep me in mind for your future publications on this theme?
I would be very grateful to have the opportunity to repeat and confirm your experiments.  As you may know, I have been working for some years on genetic recombination on E. coli K-12, which appears to be a somewhat different system from yours.  It appears most important to compare the modalities of genetic recombination and of transformation.
A repitition of your experiments would only be meaningful with the same strains which you employed, since your own work shows, as expected, a high order of strain specificity.  May I enlist your assistance therefore in supplying me with requisite cultures?  The strains which I should most like to have for this purpose are "E. coli 1", UQ; SG, and a culture of an E. coli 1 type which has been induced to mutate to sucrose-oxidation.  (I am especially anxious to have in hand a transformed type in order to know what to look for, especially as there may be unavoidable differences in our analytical techniques.)  Your cooperation will be greatly appreciated.
Yours sincerely,
Joshua Lederberg,
Associate Professor of Genetics.