6 April 1959
To: Dan Campbell
From: Linus Pauling
Subject: Experimental work proposed by Professor Campbell
I have been thinking about the work that you suggested in your talk with me today.
It seems to me that your idea is an extremely good one, and that it would be well
worth while to carry out an experimental investigation. Possibly the experiments
could be devised in such a way that some were carried out by the Ford Foundation group,
and others carried out by you, in your laboratory.
Let me summarize the argument, as you presented it to me. You said that it might
well be that an embryo manufactures proteins that are different from those manufactured
by the adult of the same species, and that in case that some protein from the mother
passed the placental membrane, it could affect the developing embryo in such a way
as to cause an abnormality in the growth of some organ. You also pointed out that
it might not be necessary to assume that the embryo manufactures different proteins
from the adult organism. Development of an organ in the embryo might depend upon
having the various proteins that are being manufactured by the growing embryo present
in certain relative concentrations, such that if the relative concentrations were
seriously disturbed there would be an abnormality in development. The increase in
concentration of one protein that might result from passage of that protein through
the barrier separating the embryo from the mother might then lead to abnormalities
You suggested that it would be worth while to see whether brain protein, for example,
injected into the developing embryo would cause an abnormality in development of the
If I remember correctly, you said that Ebert had shown that the injection of proteins
of an adult frog into the developing frog embryo caused abnormalities in development
of the embryo. I do not know how specific the abnormalities were - that is, whether
the organ affected was the one from which the adult protein had been obtained.
I believe that you said that the frog experiment is the only one of this sort that
had been carried out.
I look forward to talking with you more about this possible field of research.
cc: Dr. Lippman, Dr. Perry