February 19, 1948.

Tr. M.M@.Rhoades,
Tert, of Botany,
Columbia University,
New York 27, N.Y.

Dear Mareus,

By now, I hopea, you should have geturned from your southern
trava@a@s, which I hépe you enjoyed. So, I'm chancing this letier.

Being on the staff o8 a Genetics Lepartment is enlightening as
well as fun. A few years of it and I shell have learned enough from
stucents in seminars to compensate for my luck of any course in it.
¥y only tesching responsibilities are quite voluntary: an adavancec
graduate seminar, and an informal group mainly trom other depts.
where we diseuss microbial evenetics. The rest of the time i Go re-
search, uncer continually improving conditions. I have been spending
wost of my time on e study of the cenetic control of a bacterial
enzyme: lectozymase, have been surprise to find that not one dut
at least eight loci can mutate to give 2 lactose-nercative phenotype.
some of these mutations ere cpecifie and phenotypigally indistin-
gquishabjexxx others are rather complex, with no very apparent simple
cheriical basis. I have been particularly interested in phenotypic
reversion: of these muterts wnich turn out not to be reverse mutations,
and have pickec up a few. These may represent the development of
"new gene forms ". E don't yet know quite whst to make of all of
this, except that I have écvelored sam acute case of skepticism con-
cerning the "one-to-one" ticouy. Too bad, because that is such a
beautifully simple, neat generalization. If that goes by the board,
how sre we going to wnalyse gene setion. Souevime, L'il «sk Th. D.
for his reactions.

In tocays seminar we discussed preferential segregations, including
treat of ab-K in maize megasporogenesis. Lo you know whether there is
any interaction between the segregation of the "ab" and crossing over
between it anc ths centromeres? A little aifferently phrased, is the
biassed spindle the first or the second division? 1t is a little
easier for me to visuslize an orientation 2t the 24 since the lower
Spincle wouid thei see the other division figure apically and « cell
wall basally. Eegey the two "ab" segments wight be mutually repellent
even at long range. Have you any devastating data? Another query?
do you xuow of any suppressox mutations in maize that might be com-
parable to the one reported in Neurospora recently by itchell?

Esther is getting her teeth into a problem that may interest you:
the genetic control of mtability in these Lac- mitants. Tlifferent
svocxs show considerable variation in the rate of spontaneous rever-
Sion. Wetil be Last in April, anc hore to see you then. Fest
regards,