A Discussion on the interchange of Gases in the Lungs. 363 



will not allow oxygen to pass even under the pressure of an atmo- 

 sphere. Professor Charles regarded the conclusion as inevitable that 

 the secretory power of the epithelium was concerned in transference 

 of oxygen from the air cells to the Haemoglobin. 



j)r. Norris of Portsmouth and D^- Maybury of Southsea made some 

 observations on the prevailing theories. The latter referred to the fact 

 that pure atmospheric air had proved very useful in the treatment 

 of Phthisis. Professor Pembry of Charing-Cross London Medical school 

 was of opinion that we should confine our explanations ot gaseous 

 interchange in the lungs within the strict limits of diffusion laws. The 

 vitalistic theory sought to transfei- a part of the causes of the inter- 

 change from a known to an unknown ground. 



D^'- R. J. Anderson said that the secretion theory was very cap- 

 tivating. During the expansion and contraction of the lungs in re- 

 spiration the calibre of the endothelial cells altered, and their powers 

 as secreting agents could thus better be understood. The apnoea 

 induced by artificial respiration though due to pressure on the mu- 

 cous membrane of the air passages is more pronounced with oxygen 

 in proper mixture, it is not increased by increasing or renewing the 

 oxygen beyond a certain amount, and Ozermak long ago showed that 

 it was produced in simple respirations if these were often repeated 

 and deep. Just as the limit of the beneficial increase of Oxygen in 

 the air is soon reached, so the conditions in plant assimilation, though 

 rendered more favourable by increasing the amount of Carbon dioxide 

 in the air up to 8 per cent, are not rendered more favourable beyond 

 that limit. The presence of Argon and minute traces of other sub- 

 stances may affect the diffusibility of oxygen through the lung mem- 

 branes. Professor Bohr found that the air which accumulated in the 

 swiming bladder after aspiration contained more oxygen than the air 

 first withdrawn. 



The secretory activity of glands is often, if not generally, attended 

 with the secretion of gases, perhaps the result of metabolism of the 

 gland tissue. This has been proved for the Intestine, for the Bile 

 (Charles) and Salivary Glands (J. Barcroft) and other secretions. 



