Clones; Transformation; Strand Recombination in Vitro 



293 



B 



figure 22-1 (above). Electron microscope 

 photographs of Escherichia coli. A. Whole 

 cells in which nuclear bodies are revealed as 

 less dense areas. Original magnification 3000X, 

 present magnification about 12,000X- (Cour- 

 tesy of E. Kellenberger.) B. Thin section 

 showing nuclear bodies and the fine DNA- 

 containing fibers within them. Original mag- 

 nification 10,000X. Present magnification 

 about 15,000X. (Courtesy of W. H. G. 

 Schreil.) 



figure 22-2 (right). The geometric increase 

 in the number of bacteria due to vegetative 

 reproduction. 



V-l HOUR 







A A A A 



00000000 "■ 



1 HOUR 



HOURS 



n 3t 

 2 = 2 



t HOURS 



