September 26, 1953

(
Dr. J. L. Howatt 1 |
Drawer 940 i
Fredericton, N.B. S|

Om
Dear Dr. Howatt:

       
   

1343 9 (thr netics,32:514, table 5])

sbated |to require eonine + methionine, received from
B.D. Davis. /)
— “a
We1361 "xX prolingless .

m§.4n 58-161 [Proc. Nat. Acad. Sci.US 31:217))

proling + methionine. also from Davis.
34s and vi

  

61 are both ultimately derived from E, ecli strain K-12,

a - lineless from FE. coli strain B]
w-1669—~"leucineless " " n " nj from A. Nowdek

These strains hhve not recently been checked for purity and authenti-~
city. Please call ay attention to any anomalous behavior.

I am also sending some reprints covering techniques for the isolation
of auxotrophic mitants.

Yours sincerely,

Joshua Lederberg