1912.] Blood Gases during the Respiration of Oxygen. 



61 



calculated from 10 experiments is 16-67, giving an average percentage 

 saturation of the haemoglobin of 89 - 62 ; 67 per cent, higher than in the 

 case of animals breathing air. But it is noticeable that the average 

 haemoglobin percentage for cats breathing air is 92-65, and for 10 cats 

 respiring oxygen it is only 90'05. It would seem evident from these 

 experiments that the inhalation of oxygen does not necessarily augment 

 the quantity of oxygen in the blood, nor does it appear to affect the quantity 

 of carbon dioxide. 



On reference to Table II it will be seen that the average carbon dioxide- 

 content of arterial blood in 13 experiments was 38-43 c.c. per 100 c.c. of blood, 

 or 70-9 per cent, of the total gas. With animals in a state of hyperpnoea,* 

 this falls to an average of 20'56 c.c. per 100 c.c. of blood, or 587 per cent, of 

 the total gas, the oxygen remaining practically the same. In experiments 

 with hirudinised blood in vitro the carbon dioxide is only 3 "83 c.c. per 100 c.c. 

 of blood, or 16 3 per cent, of the total gas. 





Cats breathing 

 air (average of 

 13 experiments. 



(1) 



Cats in state of 



hyperpnoea 

 (average of four 

 experiments).* 



(2) • 

 Blood shaken in j 

 air until saturated 

 with oxygen 



experiments). f 



Total gas 



53 -76 



35 -02 



23-45 



co 2 



38 -43 



20-56 



3-83 





14 -22 



13 -50 



18-57 



The oxygen-content is of some importance. In Table II the average 

 oxygen-content per 100 grm. of blood in 14 experiments is 14-22 c.c. In the 

 various experiments the values vary considerably, from 10 c.c. to 17 c.c, and 

 the percentage saturation of haemoglobin is also variable, the average being 

 83 to 84 per cent. In the cats in a state of hyperpnoea the average is 13'5 

 not very different from many of the values found in quiet respiration. It 

 would appear from our experiments that the state of hyperpnoea affects the 

 carbon dioxide output rather than the oxygen intake. From the experiments 

 we have already published, it is clear that it takes a considerable time for 

 blood in vitro to become saturated with oxygen at 38° C, when exposed 

 to air. 



From these experiments it is a fair conclusion that during its passage 

 through the pulmonary capillaries the blood is rarely fully saturated with 

 oxygen even when oxygen is inhaled. For an explanation, it is probable 



* '.Journ. Physiol.,' 1910, vol. 41, p. 61. 



t 'Journ. Physiol.,' 1912, vol. 43, No. 6, Table III, p. 410. 



