Figure 5. Spectrogram of a 



suspension of human red blood 



cells before settling, showing no 



Soret band absorption. 



Figure 6. Spectrogram of a 

 settled suspension of human red 

 cells in the Soret band region, 

 showing the Soret absorption 

 band at 414 "5 m/i and a faint 

 extra band at 378 /;//'. 



Figure 7. Record from a 

 Siegbahn photometer of a spec- 

 trogram of a settled suspension 

 of human red blood cells in a 

 layer 1 "3 cells thick. 



Figure 9. Spectrogram of a 

 35 per cent solution of Hb0 2 

 in a 5/i layer, showing Soret 

 band at 414 5 m/i but no band 

 at 378 /;;/'. 



