laboratory. (F: 668-675, 704-714, and n.8). 
Indeed, Griffith's original demonstrations of 
transformation was carried out by injecting mice with both 
9/ 
nonvirulent and heat-killed Pneumococcus Evidence is 
accumulating from in vitro experiments that plasmids exhibit a 
range of efficiency of transformation and that the efficiency 
is generally quite low (F: 668-678 and n. 10) . Though 
it has been found to occur in animal hosts, Curtiss has 
concluded that " ... it is ... unlikely that transformation 
would be a very significant factor for gene flow in nature 
for most gram negative organisms."—^ The ability of most 
bacteria to exchange DNA by this process is unknown and 
the mechanism of transformation is unknown. 
Maturin and Curtiss have shown that DNA is rapidly 
degraded by nucleases in the small intestine of rats, thus 
providing a measure of confidence that DNA does not pass 
12 / 
through mammals intact. — Hoskins has found that one 
8/ A. H. Sturtevant, A History of Genetics (Harper and Row, 
New York, 1965); G. S. Stent, Molecular Genetics (W. H. 
Freeman and Co. , San Francisco, 1971) ; M. J. Wigler et al. , 
Cell , 11 (1977), 223-232; M. J. Bibb et al . , Nature , ~?7T~ 
(1978), 398 t 400; R. Curtiss III, Annual Review of Microbiology , 
70 (1976) ,. 507-533; E. Rothenberg et al. , Nature, 269 (1977), 
122-126; and N. J. Maitland and J. K. McDougall, Cell, 11 
(1977) , 233-241. 
9/ Stent, o£. cit . 
10 / Bibb et ad. , 0 £. cit . 
11 / Curtiss , 0 £. cit . 
12/ L. Maturin Sr., and R. Curtiss III, Science, 176 (1977), 
216-218. 
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