March ll, 1953

Dear Dr. Hungate:

Your requests sre no inconvenience at all, and I am delighted to comply.
Please do not hesitate to consult with us if we can be of further assistance
in any way.

I am encios&ng a well-used sample of velveteen, as we use it in replica-
plating. It is a fairly standard twill-back, cotton, velveteeh and you should
be able to get it in any large department dtore, or from Sears Roebuck, efc.
The fabric is not toc critical: you want as tight a weave as possible, and not

too high « nap. If you should find anything better than this, please let us know;
we have not been able tc.

Also enclosed ars two cultures, K-12 as requested, and another: 'N-1485".
This is a lambda-sensitive mitant directly derived from K-LZ. You may have a bit
less trouble with it in mtagenests experiments, as there will be no possibility
of induced lysis (a la Lwoff}, which takes place under certain ccnditions with
K-12. In addition, we are using #-1485 rogtinely in building up cur own meagre
hoard of mtante for purposes of genetic analysis. We would be very grateful
to receive back any mtants in these lines for which you may have no further use.

W-1485 can be readily lysogenized again to give the equivalent of the original
K-12 .

Underyeeparate cover I am sending some relevant reprints, and will be happy
to continue exchange.

Yours sincerely,

Josma Lederberg

Dr. Frank P. Hungate
Hafiford Works
General Electric Co.
Richland, Wash.