372 RESPIRATION 



Duke of Abbruzzi's expedition would only be about 31 mm., and 

 the CO 2 pressure about 2 1 mm. The figures, according to a form- 

 ula of Henderson, 11 would be oxygen 38 mm., and CO 2 15 mm. 



Acclimatization would be a very incomplete process if it de- 

 pended solely on the increased breathing observed at high alti- 

 tudes. In spite of increased breathing and coincident increased 

 saturation of the arterial blood owing to the alkalosis produced, 

 there is at first very distinct cyanosis when persons first go to a 

 high altitude. On Pike's Peak this was very striking, though in 

 different persons the degree of cyanosis varied greatly. The fact 

 that there was so much cyanosis although the mean alveolar oxy- 

 gen pressure was about 50 mm. sufficient in presence of the 

 lowered alveolar CO 2 pressure to saturate the haemoglobin of 

 average human blood to 85 per cent or more is now explicable 

 by the fact that, as explained in Chapter VII, the oxygen pressure 

 of the mixed arterial blood is very appreciably below that of 

 the mixed alveolar air, and particularly at lowered atmospheric 

 pressure. The cyanosis disappears, however, after a day or two, 

 or sometimes longer, of mountain sickness; and in persons who 

 have reached the high altitude by gradual stages, as in the Him- 

 alayas, there may, apparently, be little or no cyanosis, and certainly 

 no mountain sickness. Among the party of four Europeans with 

 the Duke of the Abbruzzi, who gradually reached a height of 

 24,600 feet in the Himalayas, there were no signs of mountain 

 sickness or undue exhaustion at any stage. In the account of the 

 expedition the conclusion was even drawn that "rarefaction of 

 the air, under ordinary conditions of high mountains, to the 

 limits reached by man at the present day (a barometric pressure 

 of 12.28 inches or 312 mm.) does not produce mountain sick- 

 ness." 12 Mountain sickness, and its accompaniments were con- 

 sidered to be "in reality phenomena of fatigue." The writer of 

 this account was not aware of the fact that mountain sickness is 

 easily produced in unacclimatized persons without any fatigue, 

 and occurs quite readily in persons sitting in a steel chamber or 

 going by train to a high altitude. 



We may contrast the experience of the Duke of Abbruzzi's 

 party with that of Hasselbalch and Lindhard in their steel 

 chamber. 13 They started altogether unacclimatized, from the sea- 

 level air pressure of Copenhagen, and only reduced the pressure 



n Y. Henderson, Journ. BioL Chem., XLIII, p. 29, 1920. 



12 Filipo de Filippi, Karakouram and, Western Himalaya, London, 1912. 



18 Hasselbalch and Lindhard, Biochem. Zeitschr., 8, p. 295, 1915- 



