62 THE ACTIVE FORCES OF LIVING ORGANISMS 



ignite,* so that one would be inclined to regard the 

 normal pressure at sea-level as the most favourable 

 for chemical action. Alcohol when taken at a great 

 height produces less effect than at sea-level, though 

 this may be attributed partly to its more rapid 

 elimination through the lungs and partly to other 

 causes. Speaking in general, therefore, diminution 

 of atmospheric pressure tends to restrict chemical 

 action. To what extent, however, this would hold 

 good in physiological processes it is probably im- 

 possible to say. 

 Observa- The viow that oxidation is, in the absence of 

 individuals Counteracting influences, diminished as one ascends 

 Alps. to very high altitudes receives confirmation from the 

 physiological results of many ascents and experiments. 

 When Tyndall, at the top of Mont Blanc, sank down 

 and fell asleep. Hirst woke him after a short while, 

 exclaiming : ' You have given me a fright. I did not 

 hear you breathe a single time, although I listened for 

 it for some minutes.' Mosso, having taken respiratory 

 tracings of two soldiers at Turin, which is 276 metres 

 above sea-level, and at the Queen Margaret's hut, at a 

 height of 4,560 metres, observed that although in one 

 case the respiratory frequency was increased, yet in 

 both the depth of respiratory movements was strikingly 

 diminished. Experiments on other persons yielded 

 like results, and were carried out so far as possible 

 under similar conditions at the high and at the low 

 level. One notable feature of breathing at great 

 * Foster, loc. cit., p. 612. 



