73 
act on higher forms of life is only imper- 
fectly understood. By adding to this arse- 
nal freakish forms of life — prokaryotes 
propagating eukaryotic genes — we shall 
be throwing a veil of uncertainties over 
the life of coming generations. Have we 
the right to counteract, irreversibly, the 
evolutionary wisdom of millions of 
years, in order to satisfy the ambition 
and the curiosity of a few- scientists? 
This world is given to us on loan. We 
come and we go; and after a time we 
leave earth and air and water to others 
who come after us. My generation, or 
perhaps the one preceding mine, has 
been the first to engage, under the lead- 
ership of the exact sciences, in a destruc- 
tive colonial warfare against nature. The 
future will curse us for it. 
Erwin Chargaff 
350 Central Park West, 
New York 10025 
References 
I. B D. Davis. R. Dulbecco. H. N. Eisen, H. S. 
Ginsberg, W. B. Wood. Jr.. Microbiology 
(Harper & Row. New Y ork, ed. 1 , 1967), p. 769. 
a. The prohibition of experiments involving more than 10 liters 
of culture fluid containing recombinant DNAs known ~to~ make 
Harmful products, without the express approval of the" NIH 
Recombinant Advisory Committee. 
It has been suggested that the prohibition on experiments involving 
more than 10 liters of culture fluid containing recombinant DNAs known 
to make harmful products be deleted. Controversy over this prohibition 
relates to the fact that some investigators and laboratories contend 
that larger volumes of culture fluid can be safely contained by available 
special procedures and facilities. They further contend that this 
prohibition will hamper certain potential benefits of recombinant DNA 
research, such as the large-scale and/or commercial preparation of 
clinically or industrially useful materials. 
b. Use of the bacterium Escherichia coli as a recipient for 
recombinant DNA molecules. 
It has been suggested that the use of the species of bacteria called 
Escherichia coli as a recipient for recombinant DNA molecules be 
included in the list of prohibited experiments. There are, in fact, a 
large number of different subspecies (called strains) of bacteria that 
are called E. coli . All these strains share certain properties commonly 
used for the - classification of bacterial species, and they are all there- 
fore called Escherichia coli, but they also differ from one another in 
substantial ways. Because two or more bacterial strains are classified 
as E. coli does not indicate that they are identical (2, 3). Moreover, 
some of the strains classified as E. coli are known to be pathogenic 
and others are not (2, 3). The Guidelines permit the use of only one 
particular strain of nonpathogenic E. coli, called K-12 . There is 
considerable diffe~rence between the ecology and epidemiology of K-12 
and those E. coli strains that are pathogenic or commonly inhabit 
mammalian" intestinal tracts. 
