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Indiana University, Bloomington, Indiana

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quoted or reproduced without permission

mt ee Nt oe Nat ted wee a
of copyright holder.

February 8, 1949

Dr. Max Deldrilck

Kerckhoff Laboratories

Galifomia Institute of Technology
Pasadena, California

Dear Max,

I was deliszhted to get your card and appreciate very much your comment
"a beautlful lecturs" for, as you know, I have great admiration for your own and
for your judgment in such matters.

I am particularly pleased to know that you plan to pursue further the
theoretical analysis of the mutual inhibition hypothesis, It certainly neads to
be done. Parhaps it will also be helpful to those of us who want to put the
theory to a test. I have a few ideas about experimental tests and will get to
work on them aa soon after the Harvey Lecturs as possible.

Perhaps vou have heard by the crapevine, as you usually do, of the
results of my latest tests of the plasmagene hypothesis in relation to the
Paramecium antigens. I devised what I considered a critical experiment to see
whether one gene could maintain the plasmagene presumably produced by an allelic
gene. The result was negative and I am inclined to conclwie that this means
that when the critical test of mtability 4s applied to the asaumed plasmgenes,
the concept does not hold up. Of course, this 1s limited only to the antigen
case and has nothing whateyer to do with non-zens initiated cytoplasmis char~
acters like kappa or plant plastids.

I am well aware that more than one interpretation of my result is
possible. ther gene initiated plagmazenes do not exist in this case or such
plasmagenes do not have the property of mutability, or the relation between gene
and plasmagens is so delicate that even a small changes in the plasmazene makes it
impossible for the corresponding gene to maintain it. My present inclination is
to conclude that this axperiment relegates the gene initiated plasmagene to the
realm of the non-demonstrable and, therefore, uninteresting concepts, but I still
see alternatives and want to pomer over them for a while before committing my=-
self in print. What is worse, the very fact of the dependence of the two anti-
gens in my study on allelic genes is not in an entirely satisfactory condition.
The genetic results depart slightly, but significantly, from the expected 1:1
segregation in the F2 generation. Until I fully understand what this means, I
want to delay publication,

Since you have become so closely involved in what wa are doing, I
thought you would be interested in gestting this information, I hope you will
keep me informed likewise of your developments on the theoretical end, for I
believe our experimental possibilities make tha pooling of our efforts very

With beat regards to you and my other frienis at Cal Tech,

Cordially yours,

THS at