Recent Developments in the X-Ray Study of Haemoglobin 



they show up most strikingly on a planar projection of the vector 

 density along the Z-axis {Figure 6), i.e. a projection on to a plane which 

 is normal to the length of the rods. Here the rods appear as six peaks 

 surrounding the origin at a distance of 10-11 A, in the exact positions 

 of the rods in the three-dimensional synthesis. 



Figure 6. Patterson projection normal 



to x-axis. The origin is marked by a 



cross at the centre. 



{Reproduced from II.) 



Figure 7 gives a perspective view of this rod structure in an idealised 

 form. It shows the central rod sliced open along half its length, 



Figure 1. Idealized picture of rod-like feature in vector 



structure. The scale marks on the axial cross give Angstrom 



units. {Reproduced from II.) 



141 



