ADVANCED EXPERIMENTAL PHYSIOLOGY 145 



Oxygen is rendered available for the formation of methaemoglobin 

 after the oxygen of the oxyhsemoglobin has been liberated. 



/ 



Hb/ | 



x 



4Na 3 (Cy 6 Fe) + 4NaHCO 



+ 4Na 4 (Cy 6 Fe) + 4C0 2 -f 2H 2 O. 



/ 



In this case Hb / represents oxyhsemoglobin, and 



\O 



methaemoglobin, for it is held that the oxygen atoms are united 

 together in oxyhaemoglobin but not in methsemoglobin. Accord- 

 ing to some authors methsemoglobin contains half as much oxygen 

 as is present in oxyhsemoglobin and should be represented by the 

 formula Hb = 0. ' 



CHAPTER XXVI 



BLOOD. THE HJEMOGLOBINOMETER, THE HJGMA- 

 CYTOMETER AND H^EMATOCRITE 



Gowers-Haldane Hsemoglobinometer. The maximal error of 

 this admirable instrument is not more than 0-8 per cent. The 



FIG. 140. Hsemoglobinometer. 



standard solution in tube D is a 1 per cent, solution of ox blood 



saturated with coal gas. 1 The oxygen capacity of the ox blood 



from which the standard was prepared was 18-5 per cent. This 



1 Coal gas contains carbon monoxide as an impurity. 



