PHYSICAL PROPERTIES OF NUCLEIC ACIDS 467 



Fig. 9. X-ray diagram of the crystalline form of sodium deoxypentose nucleate 

 (Franklin and Gosling'^). 



except -when the nucleic acid had been treated in aqueous solution with 

 acid or alkali. The titration results further show^^ that the amino group of 

 guanine does not take part in the hydrogen-bonding in agreement with the 

 arrangement shown in Fig. 8b. 



Confirmation of the general features of the Watson and Crick formula- 

 tion, which was apparently derived mainly from geometrical considera- 

 tions, and more precise details concerning the dimensions of the helix and 

 of the unit cell have been given by the X-ray data of Wilkins et alr'^ and 

 Franklin and Gosling.""^* Fibers of the sodium salt of deoxypentose nucleic 

 acid may be prepared" with a high degree of orientation by withdrawing a 

 needle point slowly from a stiff gel of the nucleate. By suitably varying the 

 speed of withdrawal and the water content of the gel, fibers of any diameter 

 between 1 and 100 m may be obtained. Such fibers give two di.stinct types 



" D. J. Cosgrove, R. H. Garner, D. O. Jordan, and S. M. Matty, in press. 

 " M. F. H. Wilkins, A. R. Stokes, and H. R. Wilson, Nature 171, 738 (1953). 

 " R. E. Franklin and R. G. Gosling, Nature 171, 740 (1953). 

 *« R. E. Franklin and R. G. Gosling, Nature 172, 156 (1953). 

 F R. E. Franklin and R. G. Gosling, Ada Cri/st., 6, 673 (1953). 

 M R. E. Franklin and R. G. Gosling, Acta Cryst., 6, 678 (1953). 



