16 



Chapter II 



pressures of oxygen and subsequently determining the amounts of 

 oxy- and reduced haemoglobin in each sample after an equilibrium 

 has been established between the haemoglobin and the atmosphere. 



Suppose we have five closed vessels each containing a small 

 quantity of haemoglobin solution and also at the same time oxygen 

 at the following pressures, namely 0, 10, 20, 40 and 100 mm. of 



10 



20 



40 



100 



FIG. 4. The numbers denote the pressure of oxygen in mm. 



mercury. After the fluids had been shaken up thoroughly at 38 C. 

 the concentrations of oxygen would be 



(1) (2) (3) (4) (5) 



10 



760 



20 



That is : 



-00029 



of oxygen in each c.c. of fluid. 



760 

 00058 



40; 



00116 



0029 c.c. 



Now we must find out what proportion of the haemoglobin is 

 oxyhaemoglobin, and the following are figures such as we would 

 obtain : 



Vessel 



(1) 

 0/ 



(2) 



55% 



(3) 

 72/ 



(4) 



(5) 

 92% 



The best idea we can get of the relation of these numbers to one 

 another is to place the following picture before our eyes. Suppose 

 the haemoglobin in each case to be in a cylindrical tube and that 

 the oxy- and reduced haemoglobin could be separated from one 

 another, the former being red and sinking to the bottom and the 

 latter purple and rising to the top, w r e should obtain five cylinders 

 as shown in Fig. 5 corresponding to the oxygen pressures in the five 

 tonometers. 



