July 22, 1950
Dear Dr. Lederberg:
Your coli strain K-12 seems to be rapidly replacing Coli B as the standard coli strain for microbial genetics.  Could you send me a culture of K-12.
The research is going along fairly well here.  The men at the lab have been good to me and interested.  But whether the mechanism of [...] will be solved soon or not--don't know.  Have high hopes, anyway.
Sincerely,
Albert Kelner