Tributes 



from these and other relevant data to calculate the oxygen absorbed 

 and carbon dioxide yielded to the blood per minute, under the varying 

 conditions. For, on the way, he had obtained additional data, which 

 enabled him to clear up various anomalies, such as the surprisingly 

 small differences between arterial and venous blood gases in the active 

 gland, which Chauveau and Kaufmann had left unexplained. There 

 was the fact, for example, that the actual volume of oxygen obtainable, 

 per unit volume, from the bright blood flowing rapidly from the vein 

 of the active gland, might be but little less, or even slightly greater, 

 than that from the arterial blood entering it. Barcroft found that so 

 much fluid had been lost from the blood during its passage, to form 

 saliva and lymph, as to effect a material concentration of the cor- 

 puscles, and that, when due allowance was made for this and for the 

 greatly increased rate of flow, the amount of oxygen taken from the 

 blood by the active gland was actually three or four times as much as 

 that taken by the resting gland in the same time. Determinations made 

 only on blood samples, again, had appeared to show that the increase 

 in the output of carbon dioxide with activity was less than that in the 

 calculated uptake of oxygen ; but Barcroft showed that, when the 

 carbon dioxide extractable from the saliva was added to the total, the 

 output of carbon dioxide with activity was increased by an even greater 

 multiple than the absorption of oxygen, so that the respiratory quotient 

 of the gland rose with activity. 



I do not think that it can be claimed that he had solved the problem 

 which he tackled at Langley's behest ; in particular, his blood-gas 

 determinations seem to have left the disputed nature of the secretory 

 action of sympathetic impulses as much a puzzle as ever. Un- 

 doubtedly sympathetic stimulation caused secretion ; in the cat this 

 was moderate in amount and accompanied even by a mild vasodilata- 

 tion. There seemed no reason to doubt that energy was needed for its 

 production ; yet there was no definite increase in the uptake of oxygen 

 by the gland, while its output of carbon dioxide was even diminished 

 — perhaps by the output of carbonate into the saliva. And there 

 Barcroft seems to have left that aspect of the matter. 



I do not think, however, that I shall be suspected of exaggeration if 

 I suggest that this first research which Barcroft did, begun with only 

 his own student knowledge at his back and using what help he could get, 

 during the four years of its progress, from occasional consultations with 

 men who had more experience of the methods he was using, is entitled 

 to rank as one of the classics of physiology. Remember that, when it 

 was done, there was no real beginning of detailed knowledge con- 

 cerning the way in which oxidation provides energy for functional 

 activity ; the work of Fletcher and Hopkins on surviving muscle was 



