992 Summary and Conclusions 



A. Muscular effort. The muscular contractions and the produc- 

 tion of work necessary to raise the weight of the body require an 

 active consumption of oxygen, for which, at ordinary levels, the ac- 

 celeration of the respiration would suffice. But when the quantity 

 of oxygen in the blood is considerably lowered, the new expendi- 

 ture cannot be met without serious disturbances. 



And so it is not surprising to see mountain sickness appear at 

 levels considerably lower than balloon sickness; it is generally 

 quite pronounced at 4000 meters (46 cm. pressure) ; almost everyone 

 experiences it at the top of Mont Blanc (4800 meters; 41 cm.). 

 Most of the travellers in the Andes and the Himalayas feel most 

 acute suffering when they pass above the height of 5500 meters 

 (38 cm.) , as did the brothers Schlagintweit when on Ibi-Gamin 

 they reached 6880 meters (32 cm.) ; and yet these brave travellers 

 were already acclimated by a long stay in lofty regions. 



The data furnished in my experiments by the birds which, on 

 account of their restlessness, were threatened by death in a de- 

 compression which hardly affected their more quiet neighbor; the 

 impossibility of moving at a certain stage of decompression, and 

 in travellers, the extreme lassitude, the necessity of stopping at 

 almost every step, the amelioration which follows rest, especially 

 horizontal rest, all these things are entirely explained by the 

 knowledge we have of the scanty oxygen supply of the blood at 

 great elevations. 



Our analyses of the gases of the blood permit us to reject a 

 posteriori, as we have already done a priori, the theory of M. 

 Gavarret on the poisoning of mountain climbers by the excess car- 

 bonic acid which they have produced. We have seen, in fact, even 

 in the animals which have been insecurely fastened on their board 

 or table, and which contract their muscles strongly in constant 

 movements, that, far from increasing, the carbonic acid always 

 diminishes. 



Let us examine now more closely the question of oxygen con- 

 sumption, and let us compare our mountain traveller to the aero- 

 naut of whom we spoke before: let us suppose, for the sake of 

 convenience, that it is the same individual, having at normal pres- 

 sure 20 volumes of oxygen in 100 volumes of arterial blood and 12 

 volumes in venous blood. Imagine him transported to 3600 meters 

 and at rest; his arterial blood will contain 16 volumes, his venous 

 blood 8 volumes, supposing that there is no change in the intensity 

 of the metabolic processes and that no functional trouble has de- 

 veloped. But now he contracts his muscles, walks, and continues 



