' probably when the excited or activated gene breaks down. Visible light does

is a unit of inheritance. If it works.as an anzyme, it is a "Father of Enzymes"

‘duction. To suggest that genes are developed as a substitute for the catalytic

Dept. Genetics,

- . U. of Wey
Madison, Wis.,
April 27, 1949.

‘Dear Seymour,
Just recedved your interesting and imaginative letter. I'm not surprised

that the Carnegie Institution of Washington did not know where Kelner was; he
has ‘been working in Dr. Demerec! laboratory at Cold Spring Harbor, L.I. If you
want to read the scientific detuils, the work has been published in the
Proceedings of the National Academy of Sciences, I think in the.Febr..1949
issue, at any rate, Vol. .35, pp 73-79. You can't take the popular writeups

of scientific articles very seriously; instead to would be a¢ good habit to

‘start reading the current issues of the technical journaks, like the PNAS,

Science, and s0 on.

‘I think Ahat you will get.a less confused picture of the relationship
between radiation and the gene if you study Becdle's review article,
Chemical Reviews, Vol 37, ppl5-96 (1945). Radiation (X-rays, gamma rays, UV, etc).
are all potent sources of energy. The present cinception of induced mutation ~
has been that the releasé of a quantity of this energy in or near a gene made
it chemically unstable so that it would react or disintegrate; this chemical
Change would then be a mutation, but it is not something that the organism can
do anything about. Since most mutations are deleterious, it would be to the in
mediate advantage of any species to be able to prevent them, but this they cannot
do. Light reactivation of "lethal mitations" must mean thet certain wavelengths 7
of visible light may be able to "deactivate" the unstable gene. It has been ‘
found that UV-irradiated cells eventually lose the capacity to be reactivated,

not cause reverse mutations, but it may be able to reverse the firat step in the.
action of UV. I don't want to give you the idee that this problem has been solved;
far from it. Novick and Szilard are working on just the point that you eke sug-
gested— it is fairly obvious- whether visible light will prevent the complete
development of visible or biochemical mtations as well as lethals. Luria and
Dulbecco had been working on the same thing-with phage independently of Kelner. .

Now back to your letter. The gene is not a@ component of metabolism. The gene
it produces the enzymes of metabolism. Light is not a catalyst; it is a source

of energy, and in order to be used a very complicated repertory of enzymes has
to function in photosynthe&is. For these enzymes, too, genes underlgetheir pro-

 

functions of light is to put the cart way ahead of the horse. Gehe systems heve
been developed which allow the efficient utilization of light, but probably
photogynthetssis is far less ancient than genes. _

I'l] be gladdto send you a copy of "Novel Genotypes" although I can't understand
why you'd want to read it, as it kas purely historical interest. I don't know why
48rkin would put it on his reading list, except that possibly it was written in —
the simplest form possible to fit the needs of the occasion. I'm very sorry that
I can't send you reprints of other psople's work, for the simple reason that I'm
using them here ell the time for research, tesehing and writing, and simply can't
afford to let them out. Perhaps you can gét some of them at the library, or induce
Dr. Srb to loan them to you. But you know that you can have anything thet I have
in duplicate, or any of our reprints.

fA hy aN Cn Rl Rae ARE core wnt

a
    
 

   

 

ft an + certainly not * poing ‘to scoff at your ick Antentiogs ¢ of going to Caktech.: =
be It is a fine institution, and with your intelligence and enthusiaam you would
ae probably do very well, if you saw to it that you mumekx were properly prepared _
ve ° in college. But I implore. you to think veyy seriously about making ee aeen
plans now as to the precise field that you were going.to follow. Probabiy this
is unnecessary, becaise hen I was at Columbia, the last things in the world :
that I thought I would go into were genetics and bacteriology.:But can't you:
visualize what we would both be up against, let's say the minute you applied.
for a fellowship to work in genetics at Caltech..ds soon as he saw your RAMS y
‘Beadl& would identify you with me, and square us up/ There might even be some —
apparent edvantage et first, because I think that "Lederberg" would be favored.” -
ood - But then you would never know whether you were being. judged as yourself ar es
=). me. A comparison of us would be-dnevitable, and comparisons are always oddous.
-" * -Begause one of us would come off the poomer, and it-doesn't matter which one.
s- At this stage of the game, you haven't had enough laboratory and academic ”
_ * experience to know what the other opportunities are in science, and which cf-them
~ would suit you best. You'd be the first to admit that you'll haye.to learn a’
let more chemistry and biology. Why not use your imagination constructively: in
(«| getting as thorough and tuieiz fundamental a background as you can in the kaixn’)
‘basic sciences before you decide irrevocably whwt directions you will take. — >
The science of the near future seems likely to be nuclear physics and chenistry.
All of this has biological applications too, but there is an immense amount —
of research to be done in pure and biological chemistry whith isotopes. The ad !
ditional bit of experience that you've had in "electronics" can be of immeasurable
- help in that kind of direction. But it is probably too early even to indicate _..
nS what areas should be looked at; there are any number of them, and.all require
very sound and thorough training in all. of the fundamentel selences. You should *
_be familiar with the relationship between temperature and emission spectra _ ae
before you could take very seriously your own ideas on radietion effects. Bat
you've said this yourself .in your letter, and perhaps I am over-amcious in . 7
. writing this way. But the directions that you lve sggested are very disturbing
and they should be ‘thought out very carefully. 7 tae

 

 

 
 
    

 

.
eve ann

      

co ‘I note. that you're buying a & car. I hope. ‘that you ‘dontt. think: ‘thet your’ 2
“$25 is going to be the final investmant in it or-are you in with a skilled opt
-mechanic who can keep it in repair. We have been having a little trouble sy
with our Chevvy. Whatever you do, don't drive without liability insurance! -..
-Itbwould be very easy to mortgage your whole future with e $25,000. judgment se
' 4£ you happened to have an-accident; and even if it were not your fault, you'd . a
. have a lot of trouble . and expense praving it without. the degel Backing eof an ine 5
-- gurance company. "

 

awe,

vee a a a . : ze

- “Esther and I will be very "glad: to have you: wvisit with « US, “bat not on the
basis that you suggested. If I had the time, which I won't, it would-still be .
& very bad idea to have you here as a student of mine, for the reasons which
I gave above. Have you thought of doing some summer research work ¢gsometime at

' Woods. Hole or at Bar Harbor,Maine. They both offer opportunities of just the
kind thet you are looking for. It's probahly too late for this summer, but
you should make inquiries next year. Besides, both of these places: are quite
good vacation sites! If you can come here the middke or end of June, it
would be best for us; we hope to be ablé to take some sort of vacation the
end of August, and we look forward to seeing you. .

Cee

Please don't mind my "Dutch—Uncling"; but it's just a reflection of the 7
Sewanee and affection i have for you. -

ps co ot cs Sdneerely, ae i