DISCUSSION 
Huxley: One would expect that, since its temperature is 
very low. 
Pirie: But the delay is extremely long, up to a month or so, 
and it has always intrigued me that there was no rotting in the 
hibernating hedgehog. What is the antibiotic that keeps the 
hedgehog’s gut fairly clean? 
Medawar: I didn’t understand quite what you meant, Dr. 
Szent-Gyorgyi, by talking about ““complementarity”’ as a sort 
of vital property. What kind of property of the carbon atom 
is its valence? Is it a property of the carbon atom, or something 
rather vital and mysterious ? 
Szent-Gyérgi: The mysterious thing to my mind, is that the 
biochemical system is much more complicated than we believed. 
One single molecule is an excessively complex entity which needs 
hundreds of numbers to specify its electronic distribution. To 
describe aromatics we used to draw hexagons and we thought 
we had then given a full description. Now we use hundreds of 
numbers in describing an exact fit of two molecules. If one 
molecule is changed, the other has to be changed, too, so that 
they still fit. The same holds true for the third molecule with 
which the second has to fit, and so forth. So, simultaneously, 
one has to change the whole system in a very precise manner. 
I cannot imagine this happening by random mutation. Chang- 
ing one constituent only, we could make only trouble and not 
improvement. 
Medawar: You declare that it is a mystery and then describe 
it lucidly! 
Brain: You said that it is not explicable by natural selec- 
tion. 
Szent-Gyérgyi: Just random mutation would not do. 
Hoagland: Why not? I disagree with that. 
Szent-Gyérgi: There are so many things which would have 
to happen simultaneously, in the most precise manner. 
Hoagland: But natural selection is such a wasteful process 
in which every form of organization that survives represents 
thousands that have not. All we see are those that have sur- 
vived. We have a tremendous screening process and it seems 
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