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THE ISRAEL ACADEMY OF SCIENCES AND HUMANITIES

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Professor Joshua Lederberg
President Emeritus
The Rockefeller University


Dear Josh,

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During our recent meeting, you shared with me the content of a
letter written to you by Max Delbruck in the late 1940's.  This
reminded me of my own encounter with Max in 1953, in which you
might be interested.  Following is a short account of my first
meeting with Max.

During 1953, I stayed in the U.S., at Columbia University, as a
post-doctoral student and spent the summer of this year in Cold
Spring Harbor Laboratory attending the Bacterial Genetic Course.
During the summer, I met a variety of  interesting scientists who
were also spending their summer there.  One of them was Max
Delbruck, who was well known for his work on Bacteriophage.

When I got to know him better, he told me that he stopped working
on Phage, and started a new field of  research, the study of
Phycomyces.  When I asked him why he changed fields, he complained
about the "not very collegial relations" between members of the
Phage Group.  He said that many members of this group were
reluctant to exchange bacterial and Phage strains and to share
information.  He did not like the competitive relations between the
scientists in the group and therefore decided to start a different
and new field of research, the study of Phycomyces.

The research system he developed was simple and elegant.  He used
the aluminum caps usually used to cover test tubes,  filled them
with breadcrumbs, autoclaved them, and inoculated them with spores
of Phycomyces.  After the development of the Mycelia, on the bread
surface, the vertical sporangiophores started to grow rather
rapidly.  They emerged above the rim of the aluminum cap and their
growth rate and direction could be measured through a horizontal
mounted microscope.

During the summer of 1953, Max was working on phototropism of
sporangiophore growth of Phycomyces.  By putting the aluminum
caps between two light sources in the  dark room, he could show
that the sporangiophores grew in the direction of light source.
The direction of growth changed  when he alternated the direction
of the source of light at constant times.  In such experiments the
growth alternated in its direction and the growth curve when traced
through the microscope was a spiral. He found that in a dark room,
that organism was rather sensitive to low light intensities but he
found it difficult to measure the lower limits of light sensitivity
in this organism.  When he discussed with me this problem, I
suggested to him to use luminescent bacteria as a light source.

During their log growth, they emitted the amount of light
corresponding to their concentration.  The light emission was a
factor of the density of bacterial culture.  By diluting the
culture, it should be easy to calculate the amount of light which
such suspension emitted.

Delbruck's reaction to this proposal was rather violent.  "There
are no luminescent bacteria," he declared.  "Bioluminescence", he
stated, "is one of the inventions of the biologist."  It was clear
from his attitude that he had no confidence whatsoever in facts
reported by "biologists", which were, to say, the least
unreliable.

I had worked with marine bacteria from the Mediterranean, and had
some practical experience with luminescent bacteria. .  (The
classic paper describing them came from Beijerinck in Delft at the
end of the 19th Century).  Therefore, instead of disputing Max, I
decided to isolate the bacteria, which was very easy.

A few nights after our discussion, I knocked on Max Delbruck's
door, and showed him a strong light-emitting bacterial suspension
in an Erlenmayer flask.  He looked rather flabbergasted and
surprised.  But, his reaction surprised me.  He asked if I would be
ready to join him for the rest of the summer in his research on
Phycomyces, an offer I was very happy to accept.

We tried the dilution experiments that next morning and they
turned out to be successful.

Max made one provision for my  joining him in his work.  I was
forbidden to go to the library and read about Phycomyces.  Max was
so sure that the literature gave unreliable facts, and confused
descriptions, that any study of it was counter productive.

Personally, I enjoyed working with Max during this summer.  He was
very nice to me and even suggested that I continue to work with him
for a few weeks after the Bacterial Genetics Course was over, an
offer I could not accept as I had to return to New York to complete
my work there.

During this summer, when working with dilution of luminescent
bacteria as  a low intensity light source, we saw for the first
time, "Dark Adaptation" in Phycomyces.  After exposure to strong
light, it took sometimes a long time until the mold could "see" the
low intensity light.  The lag time of this response to low
intensity light, after being exposed to strong light, was
proportional to the intensity of the strong light.  This phenomenon
of dark adaptation of vision was  known and studied in men.  I do
not know if it was at this time already known to occur in plant
phototropism.

I found working with Max very interesting.  He was very different
from all other scientists with whom I cooperated until then in his
attitude to biological systems.  The possibility of objective exact
measurement and quantitations were a pre-condition for his
acceptance of essential experimental system.  He analyzed the
system we worked with according to mathematical models he
proposed.

His thinking was absolutely logical and straight.  There was
little place for chance observations of Nature, or trying to
observe new phenomena.  He wanted a system which would respond to
logical questions put to it, and give quantitative rational
answers.  I had the feeling that he brought to biology the way of
thinking of a physicist.  The mathematical analysis of the growth
curve and its response to light of the organism was his objective
in this summer.  During the summer, we also found that the degree
of response to light also depended on the spectral composition of
the light, and we were able to construct an "Action Spectrum" of
light.  I thought that such a finding indicated the existence of a
pigment, part of the mold light receptor, and suggested that we try
to extract this pigment.  Max was absolutely opposed to this
suggestion, because it involved "chemistry" and he refused to use
any chemical approaches to biology.

During this summer he also had some violent discussions with
Seymour Cohen, who tried to study the biochemistry of Phage.  Max
was absolutely sure that by asking simple questions to the system
he studied based on a mathematical model, he could really
"understand the system".

Max was very nice to me, but rather rude and aggressive when he
attended student seminars.  He interrogated the students with
questions posed to expose their inability to think logically or
show their ignorance.  I did not like this side of his
personality.  Listening to his questions to the students, I got the
impression that he believed that his "framework of thinking" was
the only valid one for the study of biology.  He did never consider
the possibility that there are other valid approaches, attitudes,
and "thought frameworks" which also could lead to the understanding
of the phenomenon of life.

For many years, I had friendly relations with Max, saw him every
few years, but we never collaborated again.


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Please be free to make any use you wish of this letter, or any other part
of our scientific or policy-oriented correspondence, or of my unpublished
papers, including postings on
the public web sites of the National Library of Medicine.

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Yours sincerely,


Alex Keynan
(Professor-emeritus
   The Hebrew University, Jerusalem)