526 



THE RESPIRATORY EXCHANGE 



are concerned, and the temperature which should be selected is 

 38, for this is the internal temperature of warm-blooded"animals. 

 Loewy and Zuntz have recently published ^the results of an im- 

 portant investigation upon the dissociation^of oxy-hsemoglobin in 

 normal blood, laked blood, and crystallised haemoglobin. The 

 method, which had previously been most often employed, was to 

 shake gas-free solutions of haemoglobin with oxygen under different 

 pressures and then to determine the oxygen absorbed by measuring 

 the remaining gas. This procedure they rejected, for owing to 

 oxidation at the temperature of the body varying quantities of 

 oxygen disappear, a difficulty which Hiifner had attempted to 

 avoid by using carbon monoxide instead of oxygen, and thus 

 indirectly estimating the dissociation of oxy-haemoglobin. The 

 method which Loewy and Zuntz employed was similar to that 

 used by Paul Bert and Bohr. Different portions of the blood 

 were shaken with appropriately graduated mixtures of oxygen 

 and nitrogen until there was an equality of pressure in and outside 

 the blood at 38 and atmospheric pressure ; a sample of this blood 

 was then placed in Pfliiger's pump, and its gases were extracted 

 and analysed ; a sample of the gas with which the blood had been 

 shaken was also analysed. Some of the results may be given 

 here, others will be considered later in relation to the causes of 

 the gaseous exchange between the blood and the alveolar air. 



The above table shows that the laked blood took up a smaller 

 quantity of oxygen, but with low partial pressures had a relatively 

 higher saturation than that of the unlaked blood. The figures 

 below give the results obtained from similar experiments with 

 different solutions made with haemoglobin obtained with and 

 without alcohol. 



