PHYSIOLOGY OF THE CIRCULATION. 121 



be in contact with the exterior of the latter. I have 

 also found that this absorption will occur through an 

 intervening layer of animal membrane. 



Since, then, all other rapid streams, while tra- 

 versing porous tubes, possess the power of absorbing 

 any external contiguous gases, since that power is 

 shown to be possessed by the streams of blood pass- 

 ing through the systemic blood-vessels, aud since 

 the general absorbing power of the pulmonary blood- 

 currents is known to be extremely active, it appears 

 to me impossible to resist the conclusion, that the 

 entrance of gases into the mass of blood circulating 

 through the lungs takes place in the same part of 

 the blood-vessels, and is effected in the same manner, 

 as the absorption of liquids. 



This view is moreover supported by some experi- 

 ments by Leroy d'Etiolles, and related by him in 

 Magendie's Journal.* He found that on causing 

 animals to breathe highly compressed air, and thus 

 increasing the external pressure acting on the blood- 

 vessels of the lung, the absorption of that air was 

 so rapid, that the whole mass of blood not unfre- 

 quently became quite frothy. 



And the whole of these considerations also tend to 

 prove the correctness of the opinion in part enter- 

 tained by Sir H. Davyf ; viz., that the atmospheric air 

 is, in the lungs, absorbed as such (for we know of no 

 power by which the oxygen could be taken into the 

 blood-vessels and the nitrogen rejected); that the 



* "Journal de Physiologic," t. viii. pp. 106 and 109. 

 f " Researches concerning the Nitrous Oxide." London, 1800. 

 pp. 429, 447, 449, &c. 



