x HAEMOGLOBIN 481 



bands are still well defined, according to Hoppe-Seyler and Gamgee, in 

 layers 1 cm. thick and containing 0*1 gramme of oxyhaemoglobin in 1 

 litre of water. Gamgee draws attention to the fact that haemoglobin 

 absorbs both the most visible as also the most actinic light. 



Piettre and Vila 1 on examining fresh, newly laked blood of 

 guinea-pigs, or solutions of oxy haemoglobin in tubes 20 cm. long, have 

 observed in the red a new band (A. = 634). The band is at once 

 formed at body temperature, and after some time at room temperature. 

 It is not seen after diluting blood with normal salt solution. 



Reduced Haemoglobin 



Reduced haemoglobin possesses two bands, a and J3, of which only 

 one occurs in the yellow-green, lying fairly in the middle between 

 D and E, and therefore in the clear area between the a and /3 bands 

 of oxyhaemoglobin. The band a of reduced hemoglobin is broader 

 than the band ft of oxyhaemoglobin, but it is less intense. 



a A597-A535 



A573-A542 (darkest part), MacMunn. 2 

 P A436-A415 



For the same place as he used in the case of oxy haemoglobin, Hiifner 

 gives the quotient of the extinction-coefficient as 0*7617. The band 

 /3 in the violet is most intense at A425. The band is therefore 

 narrower than in the case of oxyhaemoglobin, and displaced some- 

 what towards the red end. A haemoglobin solution on being shaken 

 with air absorbs oxygen, and the spectrum of haemoglobin is changed 

 into that of oxy haemoglobin, and the same holds good for blood or 

 laked blood. The oxy haemoglobin is reconverted into haemoglobin by 

 reducing agents, such as Stoke's solution (see p. 478), or ammonium 

 sulphide, or hydrazin hydrate (Hiifner). Siegfried 3 and Novi 4 use 

 also hydrosulphite, which apparently does not reduce completely. 

 The union of haemoglobin with oxygen is a very loose one, as oxygen 

 is given off on reducing the atmospheric pressure, and in a vacuum 

 even the whole of the oxygen may be removed. If an indifferent gas 

 such as hydrogen or nitrogen be passed for some time through a 

 solution of oxyhaemoglobin, the oxygen is also completely driven oft'. 

 That the carbonic acid, which is so abundant in venous blood, also 

 displaces oxygen is discussed more fully on p. 489. Whether 



1 Piettre and Vila, Compt. Rend. 140. 390 (1905). 



2 M'Kendrick's Te:dbook of Physiology, 1. 123 (1888). 



3 M. Siegfried, Arch. f. (Anatomic u.) Physiol. 1890, p. 385. 



4 Ivo Novi, Pfliigers Arch./, die gesamte Physiol. 56. 289 (1894). 



2 I 



