248 SCIENCE PROGRESS. 



no noticeable physiological disturbance, the animal experi- 

 mented on is practically under normal conditions. 



Our first experiments were made on men ; and we ob- 

 tained the very remarkable result that with about ~oj per 

 cent, of carbonic oxide in the air breathed, the final per- 

 centage saturation of the haemoglobin with carbonic oxide, 

 instead of being at least 60 per cent., was only about 33 

 per cent. The data of a single experiment may be given : — 



Exp. No. 5. Percentage of CO = "067 throughout. 

 After 1 hour 15 minutes saturation of haemoglobin = 26-6 per cent. 



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Were it the case that carbonic oxide is oxidised to any 

 appreciable extent within the body these results might still be 

 explained consistently with the diffusion theory ; for the low 

 proportion of carbonic oxide present in the blood might be 

 due to disappearance of carbonic oxide within the body. 

 There is, however, evidence of the clearest kind against the 

 occurrence of such oxidation. 



A further possible hypothesis is that blood corpuscles do 

 not behave towards oxygen and carbonic oxide in the same 

 way inside and outside of the body. There are, however, no 

 grounds for this supposition, and against it is the fact that 

 the corpuscles of defibrinated blood when re-injected into 

 the circulation appear to perform just the same functions as 

 ordinary blood corpuscles. 



It is thus very improbable that any other interpretation 

 of our experiments is correct than that some other factor 

 besides diffusion is concerned in the gaseous interchange 

 between the alveolar air and the blood. Evidently, how- 

 ever, the results can be explained on the supposition either 

 that the oxygen tension of the blood is raised in the lungs 

 to beyond that of the alveolar air, or that in consequence of 

 an active resistance offered by the epithelium the carbonic 

 oxide tension in the blood can never rise so high as in the 

 alveolar air. The latter supposition is very unlikely for the 



