Plate 2 



A. Pattern of sea gull quill, the most detailed yielded by any keratin. It 

 is of the /i-type (Fig. 7) as shown by the meridional arc at 3 '3 A and 

 by the strong spacings ( ~ 10 A and 4-5 A) on the equator. For a list of 

 the spacings see Tables 10 and 11. 



B. The cross-/? pattern obtained from Lincoln wool by treatment with a 

 solution of urea containing bisulphite and restretching (see p. 200). The 

 4.6 A formerly on the equator now appears as an arc on the meridian. 

 See Fig. 84 and compare with Plate IB. 



Figures kindly provided by Mr. H. J. Woods. 



