HARVARD UNIVERSITY 
The Biological Laboratories 
16 Divinity Avenue 
Cambridge, Massachusetts 02138 
December 28, 1979 
Dr. Donald Fredrickson 
Director, National Institutes of Health 
Bethesda, Maryland 20205 
Dear Dr. Fredrickson: 
I am writing to urge you to support the proposed 
guidelines for Research Involving Recombinant DNA Molecules, 
most recently published in the November 30 Federal Register. 
A broader knowledge of the properties of coli and the 
nature of pathogenicity has shown us that many of the original 
hypothetical dangers were exaggerated. Furthermore, specific 
experiments with recombinant DNA strains and our deeper 
knowledge of eukaryotic gene structure has shown that 
actual recombinants are innocuous. Thus I support the new 
proposed Guidelines which represent a level of regulation of 
recombinant DNA experiments comensurate with the risks of 
such experiments. 
Sincerely , 
Walter Gilbert 
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