286 Historical 



temperature, since the blood does not have time to become suitably 

 oxygenated in the pulmonary vesicles. (P. 34.) 



In addition, as M. Gavarret has shown: 



The creation of mechanical energy corresponding to useful work, 

 accomplished during the ascent, requires the production of 65 liters of 

 carbonic acid above the 22 liters of this gas which man forms per hour 

 in his capillaries to maintain his temperature. The consequences of 

 the production of so great a quantity of carbonic acid in the body are 

 apparent. 



At a great height, the respiratory and circulatory movements are 

 accelerated not only to make possible the absorption of an adequate 

 quantity of oxygen, but also to free the blood of the carbonic acid 

 which it holds in solution. But this exhalation of gas, though very 

 active, is not sufficient to. maintain the normal composition of the blood, 

 which remains supersaturated with carbonic acid; hence the occipital 

 headache, the nausea, an irresistible drowsiness, and a still greater 

 drop in temperature, from which travellers and guides usually suffer 

 above 4000 to 4500 meters. (P. 35.) 



And he concludes by saying: 



The symptoms known by the name of mountain sickness are due 

 chiefly to the great chilling of the body, and perhaps also to a cor- 

 ruption of the blood by carbonic acid. (P. 37.) 



M. Lortet was accompanied on his ascent by an English physi- 

 cian, Dr. W. Marcet, 1 - 4 who made the same experiments, and gave 

 an account of them in a special work. 



The observations were made with a thermometer placed in the 

 mouth, without pausing in the ascent, because: 



The pause in the progress upward, however short its duration, was 

 nevertheless enough to permit the body to produce heat momentarily 

 to replace that which had been expended during the act of ascent. 



The results which M. W. Marcet reached are identical with 

 those of M. Lortet: 



1. The temperature of the human body in a state of rest does not 

 seem usually to be less at great heights than at sea level. 



2. The temperature of the body invariably tends to drop during 

 the act of ascent. The amount of this drop depends almost exclusively 

 upon the time of the last meal. This drop is due to the muscular 

 movements and not to the effect of rarified air .... A rapid ascent of 

 only 328 meters was enough to cause a drop of 1.4°. 



3. The general discomfort, particularly the nausea, often experi- 

 enced at great elevations, is accompanied by a considerable drop in 

 body temperature. It is the result of the fact that the body has be- 

 come unable, because of the physiological circumstances in which it is 

 placed, to replace the heat which it has expended during the act of 

 ascent. 



