August 2, 1946.
Dear Francis:

Ed has suggested that I might be able to get credit towards my Ph.D.
here, on the basis of my medical school work, and the work on Neurospora that
I did with you. It might work, but he thought that it was a ticklish business
and that the better or more complete references were supplied, the more likely
the attempt to succeed. Could you do the very greut favor of sending a thorough
opinion of my qualifications for a doctomte in microbiology or genetics to
Dean Hart}ey Simpson, Yale University Graduate School, New Haven, Ct. ?

The sex in bacteria stuff would then be my thesis. I have to emphasize the
extra-curricular (extra P+S) work that I did.

More recombinations are coming in; we have now the four recombinatién
classes for two pairs of characters : B-R-, B-R+, B+R- and BtR¢, althokgh in
this cross, B-R- and BeR+ were parts of the parental types. But che sam thing
now for T-R+ and T+R- where T= is threonineless, B- bictinless and R+ resistance
to Tl. Also one more biochenical recombination : Ret (3 times) from B-Y-C- .

X TeP-, We have previously gotten B-P- from the same cross. There is not random
recombination of all characters, and our fablure thusfar to isolate some of

the other types can be accounted for, by linkage, or possible séaective factors,

but there is a real deficiency. Statistical analysis so far suggests two linkage
groups: threonineless being in one, B,N,P,%, C, igdtinaouiand T in the other along
with R. This is jumping a little rapidly however. Y9 threonine-leucine~'methionine-
less' is actually a pab-less; our old pab was evidently impure and mentooiekes
inhibitory. Also a pab-less in B/r. (‘rginine-methionineless % Histidine-pabless

in B/r have giver no prototrophs.}

Regards to all, hoping to see you in a few weeks,