Jan 25 46
Dear Josh:
The idea of picking up deficient mutants is very good, and I'm glad to hear the preliminary results are encouraging.  N. Fries used a similar technique (but on minimal agar) for the preliminary screening of Ophiostoma x-ray biochemical mutants -- fairly successfully.
Regarding the effect of time of incubation on appearance of mutations, I think its [sic] still worth doing, even if Demerec has done the equivalent (paper just submitted to PNAS) with x-rayed coli; plated immediately, and sprayed, after incubation 1, 2, 3, 4 etc. [ . . . ], with virus.  With both x and u.v. "ray direction [?]" there is a definite lag in appearance of resistant mutants.  For biochemicals, incubation would have to be prior to plating.
Dr. Sinnatt assures me that the tower room will be available in March -- rent free -- for the entire term of your stay if you wish.
I'll be in N.Y. this week-end -- and will give you a ring when I have time -- or will leave word with the Ryans. (I just realized you can't get this till Mon.!)
Yours, Ed. T.