1881.] On the Influence of Altitude upon Respiration. 429 



have previously quoted, found that a smaller weight of air and more 

 carbonic acid were expired at his higher than his lower station, show- 

 ing, as I have done from my experiments, that at increasing altitudes 

 carbonic acid requires the inspiration of a smaller weight of air to be 

 formed in the body than nearer to the sea level. 



A few remarks only are left to be made on the rate of breathing 

 and volume of air taken into the lungs per respiration at the various 

 stations. The expirations were counted during three minutes, as 

 each experiment was being commenced : the person submitting to 

 experiment breathing freely in the open air and in the sitting posture. 

 The mean rate of breathing was much the same for M. David and 

 myself at Tvoire and at Courmayeur, before ascending to the Col, 

 there was consequently no appreciable difference for a rise in altitude 

 of 2,265 feet. The influence of our stay on the Col, where M. 

 David's respiration increased in frequency, apparently showed itself on 

 this gentleman on our return to Courmayeur, as a reaction appeared 

 to set in at the time, and the number of expirations fell from 20" 6 

 per minute on the Col to 8*5, 7'5, 9*5, and 9*7 per minute, rising 

 afterwards to 10, 127, and 15 - 3. The cause of this change was 

 apparently the fatigue of the increased rate of breathing during the 

 three days we spent on the pass, requiring rest of the muscles of 

 respiration. In my case there was also an increase, though not so great 

 as in the former (11*6 to 15' 6 per minute), in the frequency of breath- 

 ing on the summit, which appeared to give rise to no reaction beyond 

 a slight irregularity in the respiration on our return to Courmayeur. 

 We arrived at that place from the Col on the 19th July, in the evening ; 

 M. David's experiments were begun on the 20th July, at noon, and 

 continued that day, one only being made on the 21st. Two of my 

 experiments were undertaken on the 20th and the remaining on the 

 21st, so that a longer time had elapsed in my cases since we had 

 returned from the Col : this circumstance may explain the apparent 

 absence of reaction in my own breathing. I do not ascribe, however, 

 much physiological importance to these figures, but we were much 

 struck with M. David's slow respiration at the time. 



The mean volume of air per respiration (not reduced) was in 

 my case as near as possible the same at the intermediate as at the 

 lower station (1 litre Yvoire and 0'98 Courmayeur), but it became 

 much smaller at the summit of the pass, where it fell to 0*64 litre. 

 M. David expired a mean of 0*71 litre of air per expiration at the 

 lower station, of 1"0 litre at the intermediate one, and 0*48 litre on the 

 summit of the pass. 



Conclusions. 



1. The direct influence of food as increasing the amount of car- 

 bonic acid expired was obvious in my case in a general way, although 



