250 Historical 



Longet SG rapidly reviews the observations of mountain trav- 

 ellers and aeronauts; he lists the different explanations which they 

 have given of the symptoms felt. He agrees that sudden changes 

 in the pressure can decrease the oxygenation of the blood, because: 



A certain lapse of time is always necessary for the equilibrium 

 between the gases of the blood and the outer gases to be completely 

 established, and also for the more active movements of respiration to 

 be put in harmony with the new conditions, so that the lungs absorb, 

 in a given time, almost the same quantity of oxygen as the normal 

 state requires. (First edition, p. 474; third edition, p. 560.) 



But if one stays a long time, a complete equilibrium is estab- 

 lished. In fact, he says: 



If, at each breath, the mountain dweller necessarily draws less 

 oxygen into his lungs than the plain dweller does, he compensates 

 for that by more frequent inspirations, so that, after all, in both of 

 them the same quantity of oxygen can be absorbed in the same time. 

 (First edition, p. 475; third edition, p. 561.) 



And farther on, speaking of the oxygen of the blood, he writes 

 this quite explicit passage: 



We know that the quantity in weight of a gas dissolved in water 

 is always proportional to the outer pressure; applying this law to the 

 case in question, we would reach this conclusion that the blood of 

 dwellers in regions where the atmospheric pressure is hardly 0.380 

 meters would contain one-half less oxygen than the blood of dwellers 

 by the seashore, where this pressure is 0.760 meters; but no doubt 

 the preceding law does not apply here, because some chemical affin- 

 ity interferes. (Third edition, p. 592; first edition, p. 493.) 



That was also the opinion of M. Gavarret, ST who, in 1855, 

 expressed himself as follows: 



It would be false to say that the absorption of oxygen by venous 

 blood is a purely physical fact; everything proves, on the contrary, 

 that chemical forces play an important part in this fixation of oxygen. 

 If, in fact, its absorption was a simple physical solution, while the 

 outer pressure remained the same, the quantity of oxygen absorbed 

 should increase in direct ratio to the proportion of this gas in the air 

 breathed by the animal; now the experiments of Lavoisier had already 

 shown and those of M. Regnault had proved indisputably, that how- 

 ever great is its proportion in the artificial atmospheres created 

 around the animals, the consumption of oxygen remains the same. 

 In the second place, if the composition of the air remains the same, 

 the ponderable quantity of oxygen dissolved physically by a liquid 

 varies proportionately to the outer pressure. In the hypothesis that 

 the phenomenon took place entirely through physical forces, the 

 mass of oxygen absorbed by the residents of cities situated on the 



