13/3/53

i. Armin D. Kaiser

Division of Biology

Kerckhoff Laboratori s of Biology -
Calif. rniu <nstitute of Tecanology
Pisadena, Cal,

Dear ir, Kaiser,

Thank you for your letter of February 8,which
i an sorry to unsawer with . considerable delay, Concerning your re-
quest of the lifr strain,on which you would like to test the effect
on fertility of traces of broth, I think the problezs econcermming
the behaviour of Hfr are still so unsettled,that it would help fur-—
ther researca if its distribution were withheld for the moment. ~
have made an agreenent in this connection . ith Dr. Lederberg, who
ha: also a copy of the strain.

Reprints will be sent us soon is available.

Yours truly,

L.L.Cavalli