EFFECTS ON THE LUNGS 



239 



EFFECTS ON THE LUNGS 



While studying the oxygen tension of the blood by Haldane's 

 method of contrasting the absorption of CO by shed blood and 

 blood in the living animal, Lorrain Smith found " that exposure 



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FIG. 13. Section of Lung showing Bronchial Tube and Alveoli. Inflam- 

 matory Exudation produced by 3 atm. O 2 . (Bullock and Hill.) 



of animals to a tension of 170-180 per cent. atm. 2 causes 

 in a short time diminution in the power of the lungs to actively 

 absorb oxygen, and that with a continuance of this exposure 

 the arterial oxygen falls till it reaches the level for which mere 

 diffusion of oxygen from the alveolar air might account." 



This is because a high partial pressure of oxygen exercises a 



