Tributes 



Cambridge University Natural Science Club to which J. B. had demon- 

 strated x-rays twenty years or so earlier. I had lately been thrilled to 

 the marrow by the Respiratory Function of the Blood and so I chose 

 one of its subjects — namely the acquisition of oxygen by the blood in 

 the lung. The battle of Diffusion versus Secretion was then in full cry, 

 the work of Copenhagen (as represented by Krogh) and of Cambridge 

 (Hartridge) being pro Diffusion, whilst that of Oxford (Haldane and 

 Douglas) was in favour of Secretion. Towards the end of World War I 

 direct arterial puncture had come on the scene, and to Barcroft's 

 concrete mind, seemed to offer the chance of settling the problem more 

 conclusively in the case of man than was possible with what he con- 

 sidered the more indirect carbon monoxide methods hitherto used. In 

 February 1920, as many will remember, he shut himself up for ten days 

 in the Glass Box which is still upstairs in the Physiological laboratory, 

 and with various persons on guard, including a series of undergraduates 

 from his own College, King's, he had the oxygen percentage in the air 

 of the box gradually reduced until he reached an equivalent altitude of 

 14,000-15,000 feet. The oxygen pressure in his lung alveolar air and 

 his arterial blood were then compared, both at rest and at work, with 

 a view to answering the two questions he posed at the beginning of his 

 paper. 1. Is the alveolar oxygen pressure greater than the arterial 

 oxygen pressure ? 2. If the answer to 1 is yes, is the gradient great 

 enough for diffusion to account for the quantity of oxygen which is 

 observed to pass into the blood in a given time ? 



The answer to 1 was decisive if the principle of the arterial puncture 

 method be accepted. In regard to 2, more in a moment. 



A month or two later I was busy reading up the literature for my 

 paper at the end of May 1920, and was eagerly awaiting the details of 

 the Glass Box experiment, but not daring to go direct to the great man 

 to ask him for them in advance of publication. Fortunately the speed 

 of publication was far faster after World War I than after World War II, 

 and the full account of the work done in February actually appeared 

 in the Journal of Physiology in mid-May, ten days before my own paper 

 was due. You can imagine how I fell on the Journal like a famished 

 dog on a bone. Everything was plain sailing until almost the end of 

 the paper where question 2 was taken up. Here it at once struck me 

 that a serious mistake had been made, as it must have struck any reader 

 who was steeped at the time in the Copenhagen literature. I felt it 

 great cheek to beard the great man on such a matter, especially as I 

 had never met him personally before. However, I had already had 

 engraved in me by Bayliss that ' the greatness of a scientific investigator 

 does not rest on the fact of his never having made a mistake, but rather 

 on his readiness to admit that he has done so, whenever the contrary 



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