Recent Developments in the X-Ray Study of Haemoglobin 



and extending halfway along b. Thus the contour maps cover \ of 

 the unit cell — the remaining f are related to them by symmetry. 



y=0 



Figure 3. Section of vector structure 

 through the origin. Scale in this and the 

 following diagrams 1 A == 7 mm. {Repro- 

 duced from II). 





■M w 



b ... ****- ---v 



ri- 



^ 





uc 



a/4 



Figure 3 shows the section through the origin. The peak at the 

 origin itself has been omitted ; the average level of vector density in 

 the unit cell was chosen as a kind of sea level and only the contours 

 of the islands were drawn, those of the hollows below sea level being 

 omitted. All areas above sea level are shaded. The most striking 

 features of Figure 3 are first a ring of high vector density surrounding 

 the origin at a distance of about 5 A (marked S) which contains a 

 very high concentration of vector density, and secondly a rod-like 

 concentration of high vector density which is centred at z — O and 

 runs parallel to X. This rod contains four maxima (marked a), spaced 

 at intervals of 5 A along the length of the rod. 



A survey of the other sections showed that the ring at 5 A was part 

 of a roughly spherical shell of high vector density around the origin, 

 but that the density within that shell was greatest in the plane of 

 Figure 3. This survey also revealed more rod-like structures running 



139 



