May 23, 1954
Dear Caroline:
Thank you for your letter of the 18th and for the four cultures received the following day. They will be checked through this week -- if there are any perplexities, I will write you again.
The immediate program calls for looking for a variety of auxotroph mutants as markers. Are there any of those you'd like us to keep an eye out for, or should we send you a list when we're done? This may take some time, of course.
I would appreciate having the pedigrees on the cultures, but no hurry. By the way, your letter mentioned 153.4; one of the cultures was labeled 154.4, but we number all of our acquisitions in a uniform series (WY- ), so as long as you recognize the label, it wouldn't matter.
I hope the origin of these cultures from carlsbergenisis crosses doesn't mean they'll "convert", i.e., give irregular segregation ratios: have you any information on this point? We particularly don't want to get into this problem just now.
Yours sincerely,
Joshua Lederberg