UNITED STATES
ATOMIC ENERGY COMMISSION

WASHINGTON 25, D. C.

August 8, 1955

Dear Professor Lederberg:

Thank you for your letter of August 4 and its enclosure (part
of a draft of your paper to be published in a Growth Society
Symposium). My connection with the Atomic Energy Commission
certainly slows down all my other activities, but I hope I
will succeed in not abandoning the one to which you refer.

In connection with the draft that you sent me, I would like
to make the following comment. On page B-11, lines 9-12, you
say that my model depends for its self-reproduction on "the
correct array of organized parts (the information already in-
herent in which perhaps begs the question of biological re-
production)." I cannot agree to this, that is, to the
bracketed clause in your sentence. I showed this. In the
fixed medium M (independent of the A that follows), given any
aggregate A (outside M), it is possible to specify an
aggregate Al (also outside M, and dependent on A), such,

that if Al is immersed into M, it will keep reproducing At
and producing A. Now: since M is independent of A, the
information-content of A cannot be contained in M; since

A™ can produce A, the information-content of A must be
contained in At 3; hence the information-content of Al (al is
self-reproductive!) cannot be contained in M.

Does this argumentation satisfy you?

‘eG ‘wwownasy Ven

I an,

Yours sincerely,
Gil tm Mh na

Encl. John von Neumann

Professor Joshua Lederberg

Department of Genetics, College of Agriculture
University of Wisconsin

Madison 6, Wisconsin

P.S. - I assume that you will wish me to return your type-
script; I am, therefore, enclosing it.