March 19, 1949.

Dear Max,

As I wrote in in the letter that accompanied the slants, H=168
is mitiply heterozygous for Lac, Gal, Xyl and Mtl, and I have been
doing some detailed segregation studies on it. Unlike H-72, the pre-
dominant segregants are Lac# Galf# Xyl- Mtl-. It may be more convenient
to use mannitol or xylose FB in studying this heterozygote, since
there is mich less chance of confusing segregants with variegated
colonies. There is a very marked preponderance of Lac# among the seg-
regants of H-168, and it would not be difficult to iss the few Lac~.
The segregating colonies on FMB uwac are not nearly so striking as are

those of H-72, or of H-168 on xylose mannitol.

Sincerely,