Thanks for the details on broth vs. plate recombination. After examining them, I would conclude that the discrepancy in our
results is that you get relatively few prototrophs on the plates. Perhaps your agar is too clean! In another connection, Cavalli
has compared the two methods, and agrees with my results.
I don't think I am going to do anything on this angle, because Cavalli (in Fisher's lab at Cambridge) has discovered
a derivative of 58-161 which gives very high efficiencies of recombination (nearly 100%, discounting microcolonies). In fact,
I have been able to find almost 10% of fermentative recombinants by plating cell mixtures (grown together) out on complete
EMB agar. This is the most important lead yet on the nature of the zygote, and it should soon be possible for Cavalli to find
the fusions microscopically.
Gordon Allen is due to come here Monday next, and wasn't too definite about how long he expected to remain. He has some
rather optimistic ideas on how quickly he can get through his experiments, but I am looking forward to talking with him. It's
as hot as can be here, and you can imagine how much Esther and I would prefer to spend the summer at some cool, dull place