100 THE HUMAN BODY. 



distance rapidly passed over. Gay-Lussac, who in his 

 balloon ascension rose to a height of 22,956 feet in six 

 hours, found his respiration disturbed, and greatly accelerated; 

 and having made no movement requiring exertion, he could 

 only attribute this condition to the diminution of the pressure 

 of the atmosphere. But in climbing mountains the move- 

 ment and efforts of walking are added to the influence of the 

 height; and when the difference in altitude in one day 

 amounts to 6560 feet, a notable acceleration of respiration 

 and quickening of the pulse is observed, which in many 

 instances is accompanied by a peculiar sense of uneasiness, 

 which has been termed mountain-sickness. The most remark- 

 able symptoms are fatigue or rather partial paralysis of the 

 muscular system, and especially of the muscles of locomotion. 

 This paralysis of the legs increases with every step until, 

 having gone a certain distance with increasing difficulty, it is 

 impossible to take another step. A rest of a few seconds is 

 sufficient for the muscles to regain their power, and it seems 

 as if the traveller could go on without fear of a recurrence of 

 the difficulty; but very soon it returns, and a fresh halt is 

 necessary. The higher one goes the shorter the distance 

 that can be passed without resting from one hundred and 

 fifty steps the distance falls-off to one hundred to fifty and 

 at last to twenty or thirty. Inclination to sleep, oppression 

 of the heart, and loss of spirit are sometimes added to this 

 periodic exhaustion of strength, and in some persons mountain- 

 sickness is closely analogous to sea-sickness. In others the 

 symptoms are such as are always induced in the respiration, 

 circulation, and in consequence in the muscular system, by 

 violent exercise. Thirty steps in climbing a high mountain 

 cause as much fatigue as a forced march or run on a plain. 

 Respiration, quickened by motion and disturbed by succes- 

 sive efforts, is no longer sufficient for sanguification; the pro- 

 portion between the venous and the arterial blood is no 

 longer normal; and, above all, sanguineous congestion, which 

 is inseparable from violent exertion, takes place in the lungs, 

 in the brain, and other organs. But as soon as the muscles 

 have relaxed for a few moments, two or three full in- 

 spirations rapidly relieve the congestion, while a flood of 



