234 



HEMOGLOBIN. 



But these total reflections do go on in the case of the actual coloured 

 corpuscles in a precisely similar manner to that which would occur in 

 the hypothetical case just discussed ; and the light reflected by them 

 is conditioned by, and corresponds to, the absorption of the spectral 

 colours exerted by the haemoglobin and the oxyhaemoglobin respectively. 



The visible spectrum of reduced haemoglobin. It has already 

 been stated that, when a solution of oxyhaemoglobin is reduced, the 

 two absorption-bands a and |3 disappear and are replaced by a single 

 one (7) situated between D and E, which is less deeply shaded and 

 possesses less sharply-defined edges (see Plate I., Spectrum 5). This 

 summary description must now be supplemented. 



The right-hand diagram on p. 233 exhibits fairly accurately the 

 absorption of light by solutions of reduced haemoglobin of varying con- 

 centrations. The single absorption-band (7), though occupying in solutions 

 of from 0*2 to O4 per cent, and 1 cm. in thickness, the greater part of 

 the space between Frauenhofer's lines D and E, has its centre or darkest 

 region rather nearer D than E. According to my own measurements, 

 the darkest part of the band corresponds approximately to A. 550. 



It is to be noted that solutions of reduced haemoglobin have a much 

 greater absorptive power for the rays between A and B, and a smaller 

 absorptive power for those between F and G-, than corresponding solu- 

 tions of oxyhaemoglobin. 



THE SPECTROPHOTOMETHIC CONSTANTS OF EEDUCED HAEMOGLOBIN. 



In his most recent researches, Hlifner has determined the spectro- 

 photometric constants of haemoglobin for the same spectral regions as 

 were selected by him, in the same researches, for the determination of 

 the constants of oxyhaemoglobin. 



In the case of reduced haemoglobin the respective extinction-co- 

 efficients are distinguished as s r and s' r , and the corresponding absorp- 

 tion relations as A r and A' r . 



The following are the results of Hiifner's determination i 1 



The quotient is a constant of special importance; it is 07617. 



2 r 



The value of the quotient - has also been determined by Hiifner ; 1 it 

 is 0-6541. 



The determination of the amount of oxy- and reduced haemo- 

 globin 'when both are present. Yierordt pointed out that the absorption 



1 G. Hiifner, "Neue Versuche zur Bestimmung der Sauerstoffcapacitat des Blutfarb- 

 stoffs," Arch.f. PhysioL, Leipzig, 1894, S. 140. 



