Theories and Experiments 283 



go on as in dwellers on the plains, and they are in just as good 

 health .... 



Men and animals therefore can endure very considerable varia- 

 tions in pressure without disturbance of the functions of life. It is 

 true that, since the density of the air is lessened, the air drawn into 

 the lungs contains in each inspiration less oxygen than on the plain 

 in the same volume; but the movements of respiration harmonize 

 with these new conditions. Moreover, pressure is still exerted in all 

 directions, the air penetrates all the open cavities (alimentary canal, 

 respiratory passages), the gases of the blood are put in equilibrium 

 of tension with the atmospheric air, and the normal conditions of 

 gaseous exchange are not altered in the lungs. 



The variations in the pressure of the atmospheric medium in 

 mountain ascents or in balloon ascensions are not likely either to 

 cause painful symptoms in regard to metabolism. 



But this is not true when the decompression takes place rapidly, 

 as happens in aerostatic ascensions: 



Then a certain time is needed for the equilibrium between the 

 inner gases and the outer gases to be established. When the ascen- 

 sion has been to a considerable altitude, sometimes there appears a 

 difficulty in breathing, suffocations (from expansion of the intestinal 

 gases which press upon the lungs, crowding the diaphragm upwards) 

 and local hemorrhages in the mucous membranes (probably from, sud- 

 den expansion of the gases contained in the vessels, and from rupture 

 of the capillaries). (P. 696.) 



Beside the ideas of physicians with theories we should place 

 the opinion expressed by mountain climbers. After the theories 

 and the discussions which we have just reported, it is somewhat 

 surprising to see certain travellers almost deny the effect of de- 

 compression. 



For instance, Hudson, 1 - 1 who scorning "the easy beaten path 

 which usually leads to Mont Blanc," ascended the mountain by a 

 new route, starting from Saint Gervais, states that: 



If one is careful to save his strength, he can cross the highest 

 summits without experiencing any serious inconvenience. Several 

 persons have complained of discomfort experienced at great heights, 

 nausea, drowsiness, bleeding from the nose, the eyes and the ears, 

 and I do not doubt that such symptoms are possible; but my long 

 training in mountain journeys has proved to me that they should be 

 attributed only to fatigue, to which no doubt may be added cold 

 and the rarity of the air, or rather the unusual precautions required 

 by these two circumstances. In fact, there were five of us in the 

 group, and thanks solely to care not to get tired, none of us had an 

 instant of discomfort; the same thing was true at the time of my 

 ascent of Monte Rosa. (P. 85.) 



Dr. Piachaud, 1 - 2 whose interesting observations we have already 



