94 



Information Storage and Neural Control 



C3H LUNG 



C3H BRAIN 



Fig. 6. Ultraviolet photograph of the banding of mouse DNA and Streptomyces 

 viridochromogenes DNA in a CsCl density gradient. The photograph was taken 

 after centrifugation for twenty-four hours at 25° at 44,770 rev. per minute. The 

 Streptomyces band (p25° =[l.729 gcm-^) appears at the left. Two bands with 

 mean densities of 1.701 and 1.690 gcm-^ were obtained with mouse DNA. The 

 narrow band at the right is due to the meniscus of the solution. 



two Strands have similar or grossly dissimilar average nucleotide 

 compositions. Only fragmentary data are presently available. 

 There are indications that the DNA strands of animal cells differ 

 slightly in thymine, and hence, in adenine content (14). The 

 DNA strands of the bacteriophage, alpha, have been separated 



