456 



Messrs. L. Hill and J. J. E. Macleod. 



[May 22, 



Moderate increase of the atmospheric pressure has, according to 

 Pannm and G. von Liebig,* no distinct influence on the oxygen intake 

 or carbonic acid output of man. 



Lorrain Smith also found that the oxygen tension in blood was 

 lowered by respiration in a pure atmosphere of oxygen. The tension 

 was estimated by the CO method.! 



It will be seen from these researches that nothing conclusive can be 

 asserted as to the influence of oxygen on the gaseous metabolism. In 

 the following investigation, the question is studied by an entirely 

 different method from that of previous workers, and it will be seen 

 that we obtain very constant results. 



Method employed. 



The estimations were carried out on mice. These were placed in a 

 small glass vessel, fitted with a ground glass stopper, through which 

 passes an inlet and outlet tube. Connected with the outlet tube is a 

 " T "-piece, through which a thermometer is passed so as to lie in the 

 outgoing current of air. By this the temperature of the chamber 

 was ascertained. The egress tubes were connected with Haldane and 

 Pembrey's soda lime and sulphuric acid absorption tubes, % and the 

 ingress tubes with a series of Woulfe's bottles containing soda lime 

 and sulphuric acid, so as to remove all the carbonic acid and water 

 from the atmosphere before entering the chamber. 



A gas meter was attached to the egress tube beyond the absorption 

 tubes. To study the effect of air an aspirating bottle was attached 

 beyond the meter, and to study the effect of oxygen a cylinder of 

 that gas was attached to the ingress tube.§ The intake was deter- 

 mined by the difference between the loss of weight of the mouse, and 

 the gain in weight of the C0 2 and H 2 absorption tubes. 



The following tables show the results obtained : — 



* G-. ron Liebig, ' Arch. f. dv ges. Physiol.,' toI. 10, s. 479 (1878). 

 f Lorrain Smith, ' Jour. Phys.,' vol. 22, 1897-98, p. 307. 

 % As described in ' Joura. Physiol.,' 1892, vol. 13, p. 419. 



§ The oxygen employed was Brin's. We found this to contain from 95 — 97 

 per cent, of oxygen. 



