184 AIR AND LIFE. 



to maintain life. And if one of the guinea pigs exhibits symptoms 

 of asphyxia, these are not ascribable to the nature of the atmosphere. 

 If the experiment is pursued and air further rarefied, it is not until 

 the decrease of pressure corresponds to that which obtains at the top 

 of some peaks of the Himalayas (8,000 meters, the altitude attained 

 by Glaisher, but in a state of unconsciousness) that the hitherto 

 unaffected guinea pig shows symptoms of asphyxia. Such symptoms 

 were certain to occur, since the quantity of air was decreasing all the 

 time and must at some moment become insufficient. And now the 

 experiment has proceeded far enough, as there is no necessity at alitor 

 killing the auimals, and death must surely be the result if the experi- 

 ment is allowed to continue; air is now let in slowly. Both animals 

 recover entirely, the latter in shorter time than the former. 



Now, what does the experiment show? It shows that in itself alti- 

 tude or the decrease of pressure corresponding to altitude within the 

 limits of 3,000, 4,000, 5,000 meters or even more (under 8,000 meters) 

 is not sufficient to induce asphyxia and the symptoms of mountain 

 sickness. The proof thereof lies in the fact that the inactive guinea 

 pig exhibited no asphyxic symj)toms at such altitudes. At 8,000 meters 

 these made their appearance. They were unavoidable. They might 

 have begun a little earlier, they might begin a little later — that is, at 

 rather lower or rather higher pressure — according to the species and 

 individual; but it is certain that for all organisms there is a limit in the 

 heights of the atmosphere above which air is too rare and tenuous to 

 maintain life, and asphyxia must ensue. This first fact, however, was 

 already known, and M. P. Eegnard's experiment proves nothing new in 

 that line. What it shows is that muscular effort hastens the produc- 

 tion of asphyxia or mountain sickness, and of this the active guinea 

 pig provides an excellent demonstration. IsTow, muscular effort hastens 

 asphyxia or mountain sickness because it is itself a cause of relative 

 asphyxia. The organism that works and expends energy uses more 

 oxygen, and therefore needs more than that which keeps quiet. The 

 panting which follows running, or is the consequence of rapid mus- 

 cular work with the arms, legs, or whole body, of violent exercise, 

 proves that the body requires more oxygen, and if the expired gases 

 are analyzed it is shown that carbonic acid exhalation is increased, and 

 it is clear, therefore, that more oxygen is required, since the oxygen 

 contained in carbonic acid is borrowed from the inhaled air. 



M. P. Eegnard's guinea pigs are exact representations, the one of the 

 aeronaut or of the person in the lift, the other of the Alpine climber; 

 and since muscular exertion alone induces a state of incipient asphyxia 

 it is to be expected that in rarefied air, which itself tends to the same 

 end, that condition should occur quicker in the organism ^Yhich by its 

 activity goes, as one may say, to meet it. 



Practical conclusions are easily drawn from this demonstration. There 

 is no reason for the persons who may be carried up the Jungfrau in the 



