482 CHEMISTRY OF THE PROTEIDS CHAP. 



between oxyhaemoglobin and reduced haemoglobin there exist a 

 transition form, called by Siegfried 'pseudo-haemoglobin,' is doubtful. 

 Siegfried 1 believed, and Novi 2 has confirmed Siegfried's statement, 

 that in pseudo-haemoglobin there is still present a certain amount 

 of oxygen, although spectroscopically the pseudo-haemoglobin resembles 

 reduced haemoglobin ; but Hiif ner 3 does not believe in the existence 

 of pseudo-haemoglobin, because, he says, the statements of Siegfried 

 .and Novi are simply based on visual impressions and not on spectro- 

 photometric measurements. 



The amount of oxygen which 1 gramme of haemoglobin can bind 

 Hiifner has endeavoured to determine by oft-repeated experiments, 

 l)ut the values he obtained did not agree very well owing to the 

 estimation of the percentage strength of haemoglobin being difficult 

 .and the dissociation of the oxy haemoglobin varying. To overcome 

 the second difficulty he employed CO-haemoglobin, which dissociates 

 much less. Hiifner states that 1 gramme of haemoglobin binds 1*338 

 ccm. of carbon monoxide, and as oxygen and carbon monoxide 

 replace one another in equal volumes, he concluded that 1 gramme 

 of haemoglobin also united with T338 ccm. oxygen. This maximal 

 figure was, however, only obtained approximately when very high 

 oxygen - pressures were employed. Cohnheim remarks : " This 

 number is very constant, and numerous experiments of Hiifner, 

 Dybkowski, 4 Herter, 5 Worm Miiller, 6 Setschenow, 7 and others have 

 put it beyond doubt that the maximal oxygen capacity of fresh blood 

 or of haemoglobin solutions prepared by different methods is identical. 

 Spectroscopically there is also no difference." 



Haldane, 8 however, is of the opinion that the evidence in support 

 of Hiifner's hypothesis that 1 gramme of oxy haemoglobin yields 1'34 

 cc. of oxygen " is far from satisfactory," as Hiifner's 9 original data 

 gave an average of 1'26 cc. of carbonic oxide per gramme of 

 haemoglobin, the results of individual experiments varying by as much 

 .as 1 per cent from one another. To obtain the corrected figure of 

 1'34 cc. (which, assuming that Zinnof sky's and Jacquet's determina- 

 tions of iron are correct, gives a ratio of 1 atom of iron to 2 of 



1 M. Siegfried, Arch. f. (Anat. und) Physiol. 1890, p. 385. 



' 2 Ivo Novi, Pfiilger's Arch. f. die gesamte Physiol. 56. 289 (1894). 



3 G. Hiifuer, Arch. f. (Anat. und) Physiol. 1894, p. 130 (p. 140). 



4 W. Dybkowski, Hoppe-Seyler's med.-chem. Untersuch. p. 117 (1866). 



5 F. Herter, Zeitschr. /. physiol Chem. 3. 98 (1879). 



6 J. Worm Miiller, Untersuch. aus der Leipziger physiologischen Anstalt, 5. 119 

 <1870). 



7 J. Setschenow, Pfluger's Arch, fur die gesamte Physiol. 22. 252 (1880). 



8 J. Haldane, Journ. of Physiol. 25. 301 (1900). 



9 Hiifner, Arch.f. (Anat. u.) Physiol. 1894, p. 128. 



