810 CHEMISTRY OF RESPIRATION. 



brought about in its preparation. A haemoglobin solution in which 

 alcohol is used in preparing it, combines more firmly with oxygen than 

 the blood, and the dissociation tension of the oxygen is greater in blood 

 than in such a haemoglobin solution. 



The oxygen tension may be variable, as LOEWY l has shown, with 

 different individuals, and it is not the same in the blood of different animals 

 with the same oxygen pressure; for example, it is less in cat's blood than 

 in the dog, horse and human blood. The temperature is also of great 

 importance, as the dissociation tension increases with a rise in temperature, 

 and with the same pressure the blood combines with less oxygen at a 

 high temperature than at a low temperature. The influence of the con- 

 centration of the haemoglobin manifests itself in that in dilute solutions 

 the oxygen is more firmly combined (HUFNER, LOEWY and ZUNTZ, BOHR) 

 and that consequently blood made laky with water has a lower dissocia- 

 tion tension and a firmer binding of the oxygen than undiluted blood. 



Of especial interest is the finding of BOHR, HASSELBALCH and KROGH 2 

 that the C02 present also influences the oxygen taken up, in that as the 

 carbon dioxide tension (also within physiological limits) increases the 

 oxygen taken up, diminishes. The laws of oxygen absorption must 

 be determined by determinations upon blood itself, at the same time 

 observing the temperature and the carbon dioxide tension. A series of 

 determinations made by KROGH 3 upon horse's blood at 38 and a con- 

 stant carbon dioxide tension will be given below. In calculating the 

 results in column 4 the quantity of oxygen chemically combined at 

 150 mm. oxygen pressure is equal to 100. 



In 100 cc. blood Oxygen taken up 



Chemically Oxygen Per oont 



. ~* ffiS* *; 



10 6.0 0.020 30.0 0.030 



20 12.9 0.041 64.7 0.061 



30 16.3 0.061 81.6 0.091 



40 18.1 0.081 90.4 0.121 



50 19.1 0.101 95.4 0.152 



60 19.5 0.121 97.6 0.182 



70 19.8 0.141 98.8 0.212 



80 19.9 0.162 99.5 0.243 



90 19.95 0.182 99.8 0.273 



150 20.00 0.303 100.0 0.455 



From the above table we see that even with an oxygen tension which 

 amounts to only one-half of the oxygen pressure in the air, the haemoglobin 

 is saturated in greatest part with oxygen. The dissociation is hence at 

 70-80 mm. pressure only slightly more than with a pressure of 150 mm. 



1 Arch. f. (Anat. u.) Physiol., 1904. 



2 Centralbl. f. Physiol., 17, and Skand. Arch. f. Physiol., 16. 



3 Skand. Arch, f. Physiol., 16. 



