58 ORGANISM AND ENVIRONMENT 



striking results than in the later experiments of Doug- 

 las and myself. The earlier experiments were very 

 long ones, and we were frequently exposing ourselves 

 to oxygen want for many hours at a time. We had 

 probably thus both become more or less acclimatised, 

 so that our lung epithelium reacted very promptly to 

 the slight oxygen want produced by the CO. In no 

 other way can I explain the fact that we were able to 

 breathe with complete impunity percentages of carbon 

 monoxide which in subsequent isolated experiments 

 were found to produce severe symptoms. The same 

 criticism applies to my own early experiments as to 

 the effects of definite percentages of CO. I was 

 breathing CO every day often for hours, and doubt- 

 less had become highly acclimatised to want of oxy- 

 gen, so that I underestimated the effects of CO on 

 ordinary unacclimatised persons. 



The part played by the lung epithelium in acclimati- 

 sation to want of oxygen makes it possible to under- 

 stand how mountaineers have succeeded in reaching 

 such great heights as they have. In his recent explora- 

 tions in the Himalayas the Duke of the Abruzzi 

 reached the height of 24,600 feet, the barometric pres- 

 sure being only 312 mm. An unacclimatised person at 

 this pressure is rapidly disabled completely ; but the 

 Duke's party did not suffer at all from mountain sick- 

 ness or other serious physiological inconvenience. 

 Dr. Filippi, a member of the expedition, in his account 

 of it expresses the opinion that there is no such thing 

 as mountain sickness due to rarefaction of the air. He 

 was entirely deceived by the influence of acclimatisa- 



