110 
assumption in the experiment that is published in the November issue of PNAS, 
that the treatment of EL_ col i by a calcium chloride salt followed by heat 
shock is a condition that occurs in nature. However, I would like to point 
out that Roy Curtiss apparently disagrees with this, because in his letter 
to Dr. Fredrickson, he says the following. "In terms of transformation," 
and that is the process that was used by Roy Curtiss, "this is not known to 
naturally occur in enteric bacteria. One can induce it to occur by treating 
E. coli with calcium chloride at zero degrees, and then rapidly shifting to 
42 degrees Centigrade for a one-minute heat shock." Something of that kind 
was performed by Stanley Cohen. Such conditions are unlikely to be encoun- 
tered in nature. 
Well, I can't resolve those problems, and I doubt very much whether 
they can be resolved on the spot at this meeting, but I do think it is 
important that they are resolved before decisions are made on revising the 
Guidelines in any way that depends on those areas, or, for that matter, on 
any other areas of demonstrated lack of consensus that have been shown to 
exist at the moment. So I would just like to comment that I think these 
are very important matters that need much further consideration and sustained 
attention, not a one-shot meeting in this very intense atmosphere, in which 
remarks that are made in one section may be lost for further consideration 
in another section. 
Thank you, Dr. Fredrickson. 
DR. FREDRICKSON: Thank you. 
Dr. Wright has returned to the subject of the introduction and the 
definitions. I think I would prefer that the Committee not get into that, 
but do you have questions or comments about her remarks that may bear on 
biological containment? 
If not, I would like to ask Dr. Schwartz if he would return to the 
podium. There are two members of the Committee who would like to ask you 
questions. I understand the first of these may be Dr. Neel. 
DR. NEEL: First, I would agree with Dr. Schwartz on the difficulties 
of calculating small probabilities assuming independence of the various 
component parts of those probabilities, and would welcome constructive 
suggestions as to how to better the calculation of those probabilities. 
You refer in your material here, the second point, to the Browns Ferry 
Nuclear Power Plant where a defective design did indeed come to light. It 
is somewhat comforting that under the stress of the situation, additional 
safeguards were discovered and applied. 
I am not sure what you mean by averting an incident of catastrophic 
proportions, as you refer to this. From my knowledge of that situation, 
we might have faced a developement similar to the British experience — the 
Windscale experience of ten years ago--when a nuclear power plant was tempo- 
rarily under conditions such as might have been envisioned here. It was 
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