952 Summary and Conclusions 



would already have lost a fifth of the oxygen which it ought to con- 

 tain, at 6400 meters almost a half, and so on. 



It is clear that this constitutes a pathological state, which comes 

 from the simple fact that one breathes at too low a pressure, or in an 

 air containing too little oxygen. Height sickness is the only harm ex- 

 perienced by aeronauts, if we do not take into account the influence 

 of the cold. 



B. Fatigue sickness. This is the consequence of muscular labor. 

 If labor is repeated or violent, as after the rapid ascent of a long 

 flight of stairs, fatigue sickness will be an asphyxia for lack of oxygen 

 and excess of carbonic acid in the blood. If the muscular labor is long 

 and not compensated by food, the organism will suffer from inanition. 



Asphyxia by muscular labor will hardly be produced on the plains, 

 if the labor is not too rapid; it will be easily produced on the heights, 

 according to the findings of M. Bert. But prolonged labor, whatever it 

 be, will always finally produce pathological symptoms. These must be 

 very hard to determine exactly; it is probable, however, that it is to 

 fatigue sickness that most of the pathological symptoms observed in 

 the mountains are due. 



Mountain sickness then would be a combined effect of height 

 sickness and fatigue sickness, or rather a fatigue sickness appearing 

 more quickly on account of the altitude. The more mountain sickness 

 appears at a low level, the more it depends on the factor of inanition 

 on which I have laid stress; the more it appears at a high level, the 

 more important the role which M. Bert's anoxyhemia plays. 



Mountain sickness appears to us therefore as a complex phenom- 

 enon depending on altitude, fatigue (the latter in its turn depending 

 on labor and food) and the mental impressions which MM. Javelle and 

 Forel (Bulletin, March and June) have proved by interesting exam- 

 ples. (P. 263.) 



The conclusion of this is: 



That it is impossible for M. Bert to study mountain sickness under 

 the pneumatic bell. Why? Because he experiences only the influence 

 of rarefaction, that is, height sickness pure and simple. (P. 264.) 



We make no change in our reply. Does the fatigue to which 

 mountain climbers are subjected have as its imminent cause the 

 exhaustion of carbon compounds of the muscles and blood, as M. 

 Dufour says? That hypothesis is probable, though not proved and 

 certainly incomplete. Much has been written and many experi- 

 ments have been made on muscular and nervous fatigue, and the 

 question is still full of obscurities. But after all, it does not matter 

 much whether this fatigue following excessive walking and con- 

 tinuous efforts of climbing is the result of excursions on hills 500 

 or 600 meters high, or in mountains over 4000 meters high. Now 

 the manifestations will be quite different in the two cases; and the 

 very name mountain sickness is highly characteristic. It appears 



