ATMOSPHERIC PRESSURE AND LIFE. 



321 



But all these symptoms disappeared as by enchantment so soon as I 

 respired some of the oxygen in the bag ; returning, however, when I 

 again breathed the air of the cylinder. 



S 



Fig. 3 gives the details of one of these experiments. In this figure 

 the times of the different stages of the experiment are given at the 

 foot : just above this is seen the curve which represents the rate of 

 pulsation ; and above this another curve, showing the barometric press- 

 ure in centimetres : the figures in the left-hand margin represent the 

 changes of pressure and pulsation. It will be seen that, as the pressure 

 is diminished, the pulse is accelerated. Thus, the pressure being 42 

 centimetres (answering to the elevation of Mont Blanc), the pulse- 

 jate, which at the beginning of the experiment was 60, rose to 84. 



VOL. XI. 21 



