July 29, 1922] 



NA TURE 



03 



"tions we have verified, and to them have added a third, 

 namely, that the chemical conditions under which the 

 haemoglobin is held in the red blood corpuscle confer 

 on it the peculiarly useful property of acquiring more 

 oxygen when exposed to rare atmospheres than is 

 the case with normal blood. 



s. We sought in vain for any such form of acclimati- 

 sation as might be afforded by the driving of an in- 

 creased volume of blood round the body in unit time. 

 A rather natural supposition would be that, if the 

 haemoglobin of each cubic centimetre of blood were 

 deficient in oxygen, the tissues might be fed with 

 sufficient oxygen by the simple process of giving them 

 more blood ; but this is not so. It is true the heart 

 quickened with exercise, but the quickening seems to 

 have been rather a signal of distress than a com- 

 pensatory mechanism. 



Three principal forms of compensa- 

 tion have been described : they are 

 increased total ventilation, increased 

 expansion of the chest, increased 

 haemoglobin, and increased affinity of 

 the blood for oxygen; their relative 

 importance is a matter for future 

 research. Jointly or severally they 

 may mitigate the effects of oxygen 

 want, but they cannot entirely abolish 

 them; at some altitude the human 

 frame must always succumb. We 

 were naturally somewhat interested 

 in the question of whether we could 

 foretell which of our own party- 

 would succumb most quickly, and 

 various members of the party worked 

 out systems of prophecy which differed 

 not only in character but in the pro- 

 phetic order in which the various 

 individuals would prove susceptible 

 to altitude. One of these proved 

 quite successful. It was based on 

 the determination of Bohr's diffusion 

 constant (the ratio of the quantity of 

 oxygen absorbed per minute to the 

 average difference of pressure between 

 the oxygen in the alveolar spaces 

 and alveolar capillaries) for the lung, and was 

 suggested by Prof. Krogh. The members of the 

 expedition could be divided into two distinct groups 

 — those who had a constant for oxygen of more 

 than 40 and those who had a constant less than that 

 figure. One group with the higher diffusion constant 

 suffered from obvious symptoms of mountain sickness, 

 while the other did not. It is true that of the four 

 who suffered the salient feature was different in each 

 case: in one it was faintness, in another vomiting, in 

 a third high temperature and intense headache, and 

 in the fourth deafness and indistinct vision. Only 

 further research can show whether the coincidence 

 was fortuitous, or whether any causal relation exists 

 between the diffusion constant and the tendency to 

 " seroche." The hint, however, seemed to be worth 

 taking, and in consequence an arrangement has been 

 come to by which persons intending to go to the 

 mining districts in the Andes are being tested in the 

 Rockefeller Institute in New York. 



NO. 2752, VOL. I 10] 



I must also make some allusion to the goodwill 

 which was extended to us by every one with whom 

 we came in contact in Peru, from the President 

 down to the humblest employee of the Cerro de Pasco 

 Copper Corporation. Of the manager and the officials 

 of this company we can only say that their kindness 

 in placing themselves and their resources at our 

 disposal was one of the most potent factors in enabling 

 us to achieve such scientific results as we obtained. 

 No less can be said of the officials of the Pacific 

 Steam Navigation Company. 



The problem of Everest from the point of view of 

 physiology, upon which our work in the Andes throws 

 some light, may be stated thus : 



Every cubic centimetre of arterial blood which leaves 

 the lung must contain a certain quantity of oxygen, 



expressed as a percentage of the maximum which the 

 blood can hold, if life is to be maintained at a level 

 consistent with any degree of efficiency, ft is not 

 known what this quantity of oxygen may be. The 

 following considerations, however, give some clue to it : 



(a) Let the maximum quantity of oxygen (shown 

 on the ordinate of the graph in Fig. 1) which the blood 

 can hold be called 100. 



(b) There is a certain relation in the blood for normal 

 persons between the amount of oxygen it can hold and 

 the pressure of oxygen to which it is exposed ; that 

 relation is shown in the graph labelled " normal." 

 (The partial pressure of oxygen forms the abscissa.) 

 At the sea level the oxygen pressure in the lung is about 

 100 mm. and the quantity of oxygen in the blood 

 96 per cent, of the possible load. (See the point A on 

 the graph.) 



(c) Until recently it was supposed that the curve 

 did not alter, and therefore the graph labelled " normal " 

 stood for all altitudes. 



