STANFORD UNIVERSITY MEDICAL CENTER 
STANFORD, CALIFORNIA 94305 
DEPARTMENT OF BIOCHEMISTRY 
Stanford University School of Medicine 
Area Code 415 
497-6161 
December 20, 1979 
Dr. Donald Fredrickson, Director 
National Institutes of Health 
Bethesda, Maryland 20205 
Dear Dr. Fredrickson: 
This letter is in reference to the Rowe-Campbel 1 Amendment to 
the Recombinant DNA Guidelines which appeared in the Federal 
Registry for Friday, November 30, page 69210-69251. I strongly 
support the new proposals. They should greatly speed up research 
activities, decrease unnecessary bureaucratic procedures, and in 
no way increase or alter the hypothetical hazards involved in 
recombinant DNA. 
However, I think that the proposal should be extended to exempt 
from the guidelines all homologous cloning situations that involve 
the reintroduction of cloned sequences in nonconjugated plasmids 
or lambda vectors back into the original host. I strongly feel 
that this latter category of experiments contains no hazards to 
humans, plants, animals, or the environment. 
Sincerely, 
Ronald W. Davis 
RWD/ras 
[ 561 ] 
