THE EXTERNAL ENVIRONMENT 247 



181. Mountain Sickness. The troubles due to altitude are 

 called mountain sickness, or altitude sickness (the " puna " of 

 South Americans ( 1 ) ) or, again, aviators' sickness. At a pressure 

 of about 400 millimetres, nausea, acceleration of the heart, and 

 the respiration, and difficulties of movement are apparent ; the 

 sensibility and the intelligence are slightly blunted ; and there 

 is a danger of asphyxia causing death at a height of 8,500 metres. 



Raoul Bayeaux ( 2 ) shewed that the fall of pressure reduces 

 the oxy-hcemoglobin of the blood, as is seen by autochrome photo- 

 graphs of this blood, and that the altitude sickness is cured by 

 hypodermic injection of superoxygenated liquids in small quan- 

 tities. 



A unreliable experiment by the Weber brothers led De Hum- 

 bold to state ( 3 ) that atmospheric pressure maintained the contact 

 of articular surf aces, ( 4 ) and that this was the reason for move- 

 ments being difficult when the pressure was low, as on the top of 

 mountains. 



In reality, the fatigue is here of respiratory origin, and the 

 greater the effort of climbing the more acute will be the altitude 

 sickness. When carried to the top of Mont Blanc, Janssen 

 experienced no discomfort ; Alpinists experience sickness at 

 2,000 metres, and sometimes at 1,500 metres. Balloonists, whose 

 expenditure of energy is very small, do not feel it until much 

 higher. Aviators, whose nerves and muscles are subjected to a 

 permanent tension, are the most exposed to altitude sickness. 



At greater heights than 1,200 metres travellers suffer from 

 buzzing in the ears, from headaches, and from a keen smarting 

 of the face ; they are fatigued, and their eyes close with sleep as 

 soon as they reach lower altitudes. ( 5 ) In the case of aviators 

 the effect ol the change of pressure is sudden, espeically in the 

 descent. For example, the aviator Chavez took 19 minutes to 

 rise from 880 metres to 2,0l0metres ; Morane reached 2,600 metres 

 in 24 minutes, from which distance he descended in only 2 

 minutes (!) etc. These sudden variations of pressure are one of 

 the causes of the troubles observed. To finish the explanation of 

 this subject one must note the cold and the wind, which increase 

 with the height of the ascension, the dryness, and, if one believes 

 Knockfc, the ionisation of the air. Nevertheless, no one fact will 

 account for altitude sickness. 



H V. Ducceschi (Arch, di Fisio 1st Jan., 1912). 



( 2 ) R. Bayeux (Comptes Rendus Sciences, 3rd June, 1912). 



() Comptes Rendus Sciences, vol. iv., p. 181 ; 1837. 



( 4 ) It was a question of the coxo-femoral joints (hips). 



( 5 ) Ren6 Cruchet and H. Moulinier (Revue Scientifique, 1911, p. 740). 



