May 23, 1960

Dr. Arthur Pardee
Department of Virus ResertscJh
University of California
Berkeley, California

Dear Art,

I am enclosing the data on inactivation of the ability to form P-
galactos$dase after W on the transducing phage. The value of
erg min  on the abscissa is taken from the Slope of the T2 curve
{see Luria and Dulbecco, Genetics Soc.Amer. 18t1.02, lg&), and
maybe off 20%.  Curve 3 measures the slope of the linear rate of
enzyme formation, from 90 to 240 minutes after infection with
HFT lysate of Pl lac exposed to various W doses.

I regret to say that at this point the experiment on inactivation
of the i+ locus appears to be completely negative, contrary to the
original appearances.
on the laqproperty (0, We have used lysates with 0, 8, and 10 hits
           400 and 500 seconds) and used them to
transduce the strain with the lac deletion (see curve 4). Up to
now, 8Oj80 transductants are still i' after W (50/50 i+ in the
control).  Of course, this result may have many interpretations.

I look forward to hearing more from you. With best regards,

Sincerely yours,

sel/na

S. E. Luria