Changes in Breathing and Blood at High Altitudes. 249 



In the majority of cases, the subjects were natives of the respective 

 localities. With the exception of two subjects, one of whom had been 

 at sea-level three weeks prior to the experiment, and the other, one month 

 before, at an altitude of about 1000 feet, no subject had left the place 

 at which he or she was living for a considerable time. 



The methods of determining the alveolar CO2 percentage, and of calculating 

 the alveolar C0 2 and 2 pressures, were the same as in the previous investiga- 

 tion. 



A carefully standardised Gowers-Haldane hsemoglobinometer was used for 

 determining the htemoglobin percentage, and pure CO was used for 

 saturating the blood solution. At Asheville and New York the readings 

 for the barometric pressure were obtained from the local offices of the 

 United States Weather Bureau ; at Highlands and Waynesville readings 

 were taken from an aneroid barometer compensated for temperature and 

 checked by comparison with the readings of the Weather Bureau. 



The altitude records were taken from the bench marks of the United 

 States Geological Survey, with the exception of that for Highlands, in 

 which case the elevation recorded (3850 feet) is for the Highlands Camp 

 Sanatorium, where the experiments were made, and not for the village 

 proper. 



The mean values for the hsemoglobin percentage, the alveolar C0 2 percentage 

 and pressure, and the calculated alveolar oxygen values for men, at altitudes 

 varying from 658 to 711 mm. of mercury are given in Table I, and similar 

 values for women in Table II. Normal mean values for near sea-level 

 (Oxford) are included for comparison in each table. 



The results obtained in the present and the former investigation are 

 indicated graphically in Charts I and II. 



It will be seen that taken in conjunction with the barometric pressure the 

 values for the alveolar C0 2 and 2 pressures decrease progressively with the 

 increase of altitude. Since the C0 2 values, with the exception of those for 

 Waynesville, correspond closely with the supposed values indicated by the 

 graph in the preceding paper* additional support is given to the statement 

 then made, that the lowering of the C0 2 pressure is in direct proportion to 

 the diminution of the barometric pressure and amounts to about 4 - 2 mm. or 

 10*5 per cent, of the sea-level value for each 100 mm. of diminution of 

 barometric pressure. There is a corresponding progressive fall in the 

 oxygen pressure of about 16 mm., or 16 per cent, of the sea-level value for 

 each 100 mm. fall in the barometric pressure. 



In each of the two charts a curve is also plotted, as in the former paper, 



* Ibid., Chart 1. 



