APPLIED PHYSIOLOGY 



results.* The matter has been put very clearly by 

 Pembrey : 



1 The normal animal does not increase its respiratory 

 exchange when it breathes oxygen instead of air, for its 

 metabolism is regulated by the needs of its tissues and 

 not directly by the amount of oxygen absorbed in the 

 lungs. In the case of some diseases, during which the 

 blood, owing to diminished absorption of oxygen in the 

 lungs, is abnormally venous, the breathing of pure 

 oxygen would increase the percentage of oxygen in the 

 alveolar air, and thus enable the blood in the lungs to 

 take up more oxygen. In these cases breathing oxygen 

 under pressure greater than that of oxygen in the air 

 would, for a similar reason, be effective, and would also 

 increase the amount of oxygen simply dissolved in the 

 plasma. It would appear, therefore, that there is strictly 

 no contradiction in most of the experimental and clinical 

 results, for in the normal animal breathing ordinary air 

 the arterial blood is almost saturated with oxygen, and 

 without doubt contains as much or more oxygen than 

 the tissues need. This is certainly not the case in some 

 diseases, during which the patients have derived benefit 

 from breathing oxygen.' f 



At the same time it must be remembered that the 

 phenomena of asphyxia are, to some extent, due to the 

 presence in the blood and tissues of an excess of C0 2 , 

 and this, of course, oxygen inhalation can do nothing to 

 remedy. Nor can it be expected to be of use where the 



* See Michaelis, 'Ueber Sauerstoff Therapie,' Zeit. f. didt. 

 u. phys. Therapie, 1900, iv. 122. 

 t Schafer's * Physiology,' i. 736. 



