DEPARTMENT OF ZOOL06Y

INDIANA UNIVERSITY

BLOOMINGTON, INDIANA

July 26, 1946

Dr. Sol Spiegelman
Biologl cal Laborato rg
~tologi ca~, bod ation
Cold Spring Harbr
Long Island, sew York

Dear Sol :

I still have my,notes that I used as a basis for my

comments on Lindegren s paper md can, I believe, easily
reconstruct my discussion. In case you do not get the ori-
ginal from Lindegren in the meantime, I shall rewrite this
for you and send it along vb thin a week.  At present, I am
putting every effort on trying to complete tke manuscript
of the paper I gave at the conference and think I should
keep at it until it is done for I am sure Demerec must al-
ready be uneasy about it.
this business and I can then turn my mind to the Lindegren
di s cus sion.

Another week should see me through

In regard to your question concerning the capacit of

kappa to multiply feebly in the absence of the K gene, 9
probably made some mention of this to you without going into
it in detail. We have some evidence which might be interpreted
in this way, but the interpretation is not yet clear as there
are two possible alternatives and we do not know yet which is
correct. Here is the situation. After KK killers are crossed
to kk sensitives and the killer F1 are allowed to undergo auto-
gamy we find some clones which start out a s killers,quickly
become mixed (that is, they contain both killer and sensitive
animals 1, and eventually be come en tirely sensitive .  I men -
tioned this in my first paper on killer genetics, but con-
sidered at that time only those cases in which the clom transform
into sensitives rather quickly, within 8 to 10 fissions.
This is the usual result. However, within the pst few months,
in a more intensive study of the matter,we find that there are
some clones which take very much longer to transform completely
into sensitives, some of them take 30 to 40 fissions or more.
In view of What we now know about the number of particles of
Mppa present at the start in a fdller, it is obvious that there
must be some reproduction of kappa in these clones that have so
long a lag period before kappa disappears. The basic quastion,
of course,  and one which must be answered before any interpreta-
tion can be glven to the phenomena, is whether these clones are
kk or m.  We have tested the matter only in the clones that
transform rapidly. Those am the kk clones and there is no need

-2-

to assume any reproduction of kappa in them.

We are now in

the process of analyzing the genotype of the clones that
have the very long lag periods and should have the answer
within a few weeks, If they also turn out to be kk then we
have the problem of finding out how it 5s that kappa can be
reproduced in such clones. On the other hand, if they turn
out to be KK then our problem is to account for the disapmar-
ance of kappa. I suspect that we are going to find that the
latter alternative is correct and I alreaq have a clue as to
what makes kappa dlsappear.
and we had better not go into the possibilities until we find
out what genotype is involved in these  cases.

kt, this is jumping too far ahead

1 hope you are continuing to hsm? a stimulating and

pleasant time at Cold Spring.

With best regards to you and my other friends,

Cordially yours,