!()() 



J. HKHUKHT 'I\\'\I.()H 



Fig. 12. Higher magnification of the hohcal structin-es .shown in Fig. 11. At jjlaces 

 the helices (aryuLcs) can be seen to be double and the fibrils wound into the large 

 helix have a periodicity of density indicating that this fibril is formed from a 

 helically coiled ultimate fibril of about 30 A. (Original photograph contributed by 

 George D. Pappas and PhiUip W. Brandt.) 



