Tributes 



being somewhat mystified ; * I want your blood ', was the answer. 

 And so I was duly venesected and then we walked to the laboratory, 

 Barcroft carrying a small basin of my blood which he resolutely stirred 

 with a bunch of feathers in order to defibrinate it. He thus began his 

 investigation of the properties of my blood. 



In TenerhTe we all acted as Bancroft's subjects. His experiments 

 were made at sea-level at Orotava, at the German meteorological 

 station at an altitude of 7,000 feet in the Cafiadas or great crater of 

 TenerirTe, from the centre of which the actual volcanic cone of the Peak 

 arises, and at the Alta Vista hut at an altitude of 10,700 feet, 1,500 feet 

 below the summit of the Peak. At the outset the experiments were 

 nearly frustrated by the fact that the nitrogen which he had brought 

 with him actually contained a small trace of carbon monoxide as an 

 impurity, but the difficulty was overcome by absorbing all the oxygen 

 from atmospheric air by means of a spare phosphorus pipette which 

 had been brought by Durig for use with his gas analysis apparatus. At 

 the Alta Vista hut Barcroft was slightly affected by the altitude which 

 diminished his power of mental concentration and impaired his usual 

 alertness and vigour, so he soon went back to the Canadas observatory 

 and blood samples were sent down to him for analysis. 



The results which Barcroft obtained were clear-cut and showed that 

 although the oxyhaemoglobin dissociation curve was shifted to the 

 right if the determinations were made in the presence of a carbon 

 dioxide pressure identical with that in the subject's alveolar air at sea- 

 level, the curve was substantially unaltered if it was determined at the 

 lowered carbon dioxide pressure characteristic of the same subject at 

 the particular altitude at which the blood samples were taken. 



Now at this date we were all, I think, under the impression that the 

 hyperpnoea and reduced alveolar carbon dioxide pressure in the 

 resting subject at a high altitude were due to an acidosis caused by the 

 accumulation of excess lactic acid in the blood in consequence of the 

 diminished concentration of oxygen in the atmosphere. Barcroft, too, 

 shared this view, and on his return to England he showed how the facts 

 which he had elicited in Teneriffe could be imitated by the addition of 

 appropriate concentrations of lactic acid to human blood. 



A year later, in 1911, Barcroft continued this work during an ex- 

 pedition in company with Camis, Mathison, Roberts and Ryffel to 

 Monte Rosa, observations being made both at Col d'Olen (9,500 feet, 

 barometer 542 millimetres) and the summit (15,000 feet, barometer 

 440 millimetres). The concentration of lactic acid required to cause 

 any given shift of the oxyhaemoglobin dissociation curve of normal 

 blood had already been ascertained, but when on this expedition the 

 actual lactic acid concentration in the blood at a high altitude was 



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