﻿AIR AND LIFE. 51 



under the circumstances attending the excursion, mountain sickness 

 was not to be feared. M. Eegnard's experiment answers this question. 

 As far as physiologists are concerned, the question was settled, but the 

 general public required to be satisfied npon this point. The experi- 

 ment is easily repeated in any laboratory, and it is quite unnecessary 

 to ascend Mont Blanc or the Himalayas for the purpose. All that is 

 required is a glass bell jar, an exhausting pump, and a pair of guinea 

 pigs. The bell jar must be rather wide, and it is placed — inverted — 

 upon a smooth and even surface, such as that which can be afforded by 

 a thick pane of glass. 



The edge of the jar is smeared with tallow, so that when placed upon 

 the pane the access of air is entirely i^revented. Under it are the two 

 guinea pigs. One is free and does as he chooses; the other is placed 

 in a small treadmill where he is compelled to exert himself somewhat 

 in order to preserve his equilibrium, as the treadmill is made to turn; 

 round by means of electricity. The two animals represent, the first^ 

 an aeronaut, or a person quietly sitting in a lift where no exertion is 

 required; the other, a mountain climber, who has to expend energy, 

 and to work if he wants to get to the top; and now both must be 

 placed in a condition similar to those which obtain in high altitudes. A 

 few strokes of the air pump connected with the bell are enough to bring 

 the pressure to correspond exactly with that which exists at 2,000, at 

 3,000, at 4,000 meters height, and a manometer shows the pressure pro- 

 duced. So this experiment begins, and the atmosphere within the bell 

 is slowly rarefied, as would happen in the case of a slowly ascending 

 lift or mountain climber, and because, also, rapid decrease of iDressure 

 would be most dangerous. Up to the decrease of pressure which cor- 

 responds to a 3,000 meters altitude both animals remain quite well, 

 the one who works his way up, so to say, as well as the other who 

 keeps quiet or only walks a few paces to the right or left. The process 

 is continued and the rarefaction increased. Before the pressure corre- 

 sponding to 4,000 meters altitude is attained, however, the ''working'^ 

 guinea pig manifests evidence of physiological discontent. Now and 

 then he stumbles, and does not exactly keep pace Avith the treadmill; 

 he even rolls over and is clearly out of breath. When the manometer 

 shows the pressure to be that which corresponds to a 4,C00 meters alti- 

 tude (210 meters less than the altitude of Mont Blanc), this guinea pig- 

 is entirely disabled. Ee can walk no more; rolls on his back, and is 

 rolled by the treadmill; ho moves no longer. In fact, he seems quite 

 dead. Life is not extinct, though, and the animal moves when air is 

 again let into the jar. The other animal is in an excellent state of 

 health. At no moment has he jn^eseuted the slightest sj^mptoms; he 

 nibbles at cabbage, and seems quite unconcerned with the experiment. 

 It does not affect him in the least. 



It may then be considered as settled that the quantity and quality of 

 the air contained in the jar are quite sufficient; that they are adequate 



