Tributes 



not published until 1907, six years after Barcroft's third and final 

 paper in the Journal of Physiology on the gaseous metabolism of the 

 salivary gland. He had, in fact, made the first approach to a really 

 critical and quantitative study of the gaseous exchange with the blood 

 of any organ, and its variation with controllable activity ; he had had 

 to use practically single-handed, and to adapt to his own purposes, 

 essentially cumbrous methods ; and yet he had carried it through to 

 success, with characteristically cheerful optimism. To recall further 

 the state of knowledge with which he started, we may note that 

 Volume 25 of the Journal of Physiology, in which Barcroft published 

 the first two of his full papers, contained also the description by Haldane 

 and Lorrain Smith of the determination of haemoglobin in a blood 

 sample by direct, colorimetric comparison. Barcroft was able to use 

 this method to measure the loss of fluid by the blood in passing through 

 the active salivary gland. It also contained Haldane 's second and 

 fuller description, with a defence of its accuracy, of his ferricyanide 

 method for determining the oxygen held by haemoglobin in blood. 



Barcroft was clearly accepted at once by his seniors as a new recruit 

 of the first rank to experimental physiology. A year after he finished 

 his work on the salivary gland by use of the existing cumbrous methods 

 for pumping off and analyzing the blood gases, we find him in co- 

 operation with Haldane describing the method of measuring the oxygen 

 and carbon dioxide in a small sample of blood by liberating them 

 chemically, the oxygen with ferricyanide and the carbon dioxide with 

 tartaric acid, in a small closed bottle connected with a water manometer. 

 This, of course, immediately provided Barcroft with an immensely more 

 convenient method for studying the gaseous metabolism of other 

 glands and organs, and in the following years we find him engaged on 

 such studies of the kidney with Brodie and of the pancreas with Starling. 

 In the pancreas they encounter again one of the anomalies, in the 

 absence of any conspicuous rise and sometimes even a fall in the output 

 of carbon dioxide to the blood, when the gland is made to secrete 

 rapidly by secretin, and they find the explanation for this in the large 

 amount of sodium carbonate in the secreted juice. And then, as the 

 last of the studies in that particular series, came a paper with Dixon on 

 the gaseous metabolism of the mammalian heart, in 1907, in the same 

 number of the Journal of Physiology as the paper by Fletcher and 

 Hopkins on surviving voluntary muscle, to which Barcroft and Dixon 

 were able to make passing reference in dealing with their own results. 

 The application of the method was not by any means exhausted, 

 and we find Barcroft returning, as late as 1912, to a study of the 

 gaseous metabolism of the liver with L. E. Shore. But he was, for the 

 time, diverted from it by a further simplification of the method of 



8 



