INDIANA UNIVERSITY

BLOOMINGTON, INDIANA

DEPARTMENT OF ZOOLOGY

Dr. S. Spiegelman
Carnegie Institution
Cold Spring Harbor
Long Island, N.Y.

Dear Sol:

Your discussion excited me a good deal and I immediately called a

conference of our whole laboratory group to read it to them in full. Be-
fore I got to the end of it, however, Nichael White walked in on us for a
visit and stayed for several days.
him and enjoyed his visit thoroughly, but it did mean that I had to put
aside your discussion until yesterday.
this letter reaches you. Thdt is why I sent messages to you thmu& him.

Of course, we were delighted to  have

I presume White will see you before

Needless to say, I liked your discussion very much indeed and can

well underst,and the time and effort you must have put in+& it o It seemed
to me that there was very little that needed to be written in reply to  it
alxl that little bit I am sending alors to Kiss Fisher.
you Will be able to get a look at it I am not sending a separate copy t0
you 8

Since I am sure

The main point that I raised in my reply was in regard to your pre-

dictions.
dication of any substrate limitation for the development of the killer
character.
is present in adequate concentration) the clones are invariably killers.
I think you will agree now, as we did more than a year ago, that this im-
plies that &atever substrate is required for the development of killing
is universally present in adequate amounts under our conditions of culture.
In view of Lhis situation, it is difficult for me to see why the killer
character is not always maintained when Kk plus kappa become kk,if your
prediction were applicable.  I presume you had in mind some of the excep-
tional cases that I have been writing you about, but it is not clear to me
how substrate could be the limiting factor in such rare exceptional. cases
when there is no indication of the deficiency of substrate uder our stan-
dard conditions of culture.  If you have any commerrts on this, please send
them along as I should value your comments very highly.

As you know, der our conditions of culture, we have

no in-

idhenever we have the M( plus kappa composition (providing kappa

With best wishes as always,

Cordially yours,

9