PROCEEDINGS 



OF THE 



Camlrciirg* ||ljtl0g0p(wal Sflriftg. 



Apparatus for the Analysis of the Oases w Small Quantities of 

 Blood. By Joseph Barcroft, King's College. [With Plate I.] 



The present communication consists of an account of an 

 apparatus for the quantitative estimation of the oxygen and car- 

 bonic acid in the blood coming from a particular organ. 



The general principle of analysis used in all estimations of 

 the two gases is that of exposing the blood to a vacuum and 

 removing the gases which it gives off by means of a mercurial 

 pump. 



So far, however, this principle has been only applied with 

 accuracy when considerable quantities of blood (30 — 50 c.c.) have 

 been available for each analysis, and in the case of blood drawn 

 direct from a living animal it has been necessary to take it from 

 some large vessel when the rate of flow is rapid. 



These experimental difficulties have excluded the possibility 

 of analysing the blood from special organs except in a few cases. 

 Among these cases may be mentioned the experiments on the 

 respiration of muscle by Ludvvig, Schmidt and Sczelcow. 



The object of the research for which my apparatus was 

 devised is a comparison of the arterial and venous bloods entering 

 and leaving the submaxillary gland, according as the gland is or 

 is not secreting saliva. 



In this case the samples of blood available are, as a rule, 

 about in volume 8 c.c, though sometimes only 5 c.c, and the 

 length of time taken to collect such a sample is 3 — 4 minutes. 



The object before me then has been to construct an apparatus 

 in which the working error is about ith of that of existing ones, 



VOL. XI. PT. I. 1 



