1002 Summary and Conclusions 



ties; one would have to place a gas meter on the course of the 

 inspired or expired air, observe the respiration for a very long time 

 to eliminate occasional modifications, and make observations either 

 on the same person alternately on the seashore and at a great alti- 

 tude, which would be the best but the hardest, or in a very great 

 number of persons to get averages. 



If we suppose, as is probable, that the pulmonary ventilation has 

 changed little or not at all, and if, on the other hand, the organic 

 consumption has remained at the same degree, the result will evi- 

 dently be that the percentage in volume of carbonic acid in the 

 expired air will have increased in inverse proportion to the pres- 

 sure. At a half-atmosphere, in this hypothesis, it will have doubled; 

 at two-thirds of an atmosphere (50 cm. pressure, 3300 meters, 

 nearly the height of Cuzco) it will have increased by a third, and 

 the 4.3% average on the sea level have become 6.5; at Mexico 

 (58 cm.) , where Coindet made his unfortunately unprofitable ex- 

 periments (p. 266 and 277), it should be 58 : 76 = 4.3 : x = 5.6. 

 These are data which it would be easy to study on the spot; a flask 

 of 200 cubic centimeters in which one would make a score of expi- 

 rations, so as to renew the air in it completely, could, if provided 

 with a closely fitting heated rubber stopper, serve for distant 

 analyses; I would make this suggestion to travellers sojourning in 

 lofty regions, or even to mere mountain climbers. 



But very probably the proportion for acclimated individuals will 

 be less than the calculation requires; in other words, very probably 

 the intensity of the respiratory combustions will have decreased. 

 And this probably constitutes what is called acclimatization in 

 lofty regions; I imagine that its cause is simply a lower consump- 

 tion of oxygen in a given time, an economy in the combustions, 

 which within certain limits does not hinder the completeness of 

 organic functions. I realize that I am leaving the solid ground of 

 direct experimental results to undertake a hazardous journey in 

 the unsteady realm of hypotheses; but what does it matter, if the 

 hypothesis leads us, not to imprudent conclusions, but to new and 

 fruitful researches? In this, as in so many other matters, nothing 

 ventured, nothing gained. 



Let us see then. 



Now I am persuaded that at normal pressure, we consume much 

 more oxygen in a given time than is necessary to maintain our 

 temperature at its normal and constant level, and to meet the de- 

 mands of forces required for muscular and nervous acts. Let us 

 examine the figures as the present state of science furnishes them, 



