Theories and Experiments 253 



expression which indicates, in the mind of the learned professor 

 of Montpellier, not a drop in the body temperature, but the sen- 

 sation of cold which may be produced by various causes. 



After studying these causes in a man at sea level, M. Martins 

 declares that others exist in the mountains. Some act indirectly 

 by changing the temperature of the air to which the sun gives less 

 heat as a result of its decreased density, and which receives very 

 little heat from the much reduced contact surfaces of the ground. 

 Let us add that its constant renewal does not give it time to 

 become warm, and that the expansion of ascending currents tends 

 to chill it. Other causes act directly upon the living body. 



First is the power of radiation, which is twice as great on the 

 Grand-Plateau of Mont Blanc as at Chamounix; next, pulmonary 

 and cutaneous evaporation, stimulated by the low pressure, by the 

 wind which blows almost constantly in lofty regions, and by the 

 dryness of the air; finally, on lofty summits, the contact with a 

 frozen soil. These are the physical causes which tend to chill the 

 body. After explaining them in detail, M. Martins next comes to 

 the physiological causes of the chill, which are peculiar to high 

 mountains. 



Here we quote verbatim: 



Everyone knows that, at elevations which vary according to the 

 individual from 2000 to 4000 meters, one begins to feel painful sensa- 

 tions, namely: extreme panting accompanied by headache, desire to 

 sleep, nausea, and great lassitude. This is the phenomenon called 

 mountain sickness, a complex result of fatigue, abrupt decrease in 

 pressure, and especially the rarefaction of the air. Physiologists 

 consider that man draws into his lungs in an ordinary inspiration on 

 the average a half-liter of air; the oxygen of this half-liter of air 

 combines with the blood. At sea level, at a pressure of 760 mm. of 

 mercury, a half-liter of air weighs 0.65 gm. and contains in weight 

 0.16 gm. of oxygen; at a decreased pressure, 475 mm. for example, to 

 which we were subjected for three days at the Grand-Plateau, the 

 volume of air inspired is still the same; but its weight differs, for it 

 is reduced to 0.40 gm., and the oxygen contained by this half-liter 

 of air is only 0.10 gm., and on the summit of Mont Blanc, at a pressure 

 of 420 mm., only 0.09 gm 



The oxygen of the blood and consequently the heat production 

 are therefore less than at sea level merely because the quantity of 

 oxygen drawn into the lungs is much smaller. Respiration is less 

 perfect, just as it is in foul air in which the proportion of oxygen is 

 lower than in normal air. This entirely physical cause had already 

 been pointed out by Halle, Lombard, and Pravaz junior. Like them, 

 I attribute to it the symptoms of panting which are noted in rapid 

 ascents on lofty mountains. 



The objection that on lofty mountains the number of inspirations 



