254 Miss M. P. FitzGerald. Further Observations on the 



seven atmospheres in the case of Greenwood. With long exposures, however, 

 the result may well be different. 



The percentage of haemoglobin in the blood in men increased progressively 

 with the fall in barometric pressure. The mean percentage values correspond 

 closely with the supposed values at similar pressures indicated in Chart III 

 of the previous paper* and support the statement there madef that " for every 

 100 mm. fall of atmospheric pressure, there is an average rise of about 10 per 

 cent, in the haemoglobin." Similar, but less regular, increase occurred in the 

 percentage of haemoglobin in the blood of women. An unusually low value 

 (91*8 per cent.) was recorded at Highlands. Insufficient data together with 

 varying physiological condition may account for the irregularity in the 

 records for women. 



At each locality greater uniformity in the individual determinations was 

 met with than in the previous investigation at the higher altitudes. At 

 Waynesville and Asheville, in four of the five men subjects aged between 

 52 and 64 years, the haemoglobin percentage was less than 100, which 

 possibly indicates that the compensatory increase of haemoglobin in the blood 

 wanes with age at the less high altitudes. 



With regard to the influence of age on the fall in the alveolar CO2 pressure, 

 the tendency previously noticed! for the fall to be less in those under 30 than 

 at later age periods was again observed. Only one subject complained of the 

 ill-effects of living at high altitudes (3850 feet). A marked difference was 

 observed in the degree of " nervousness " in the subjects, this being much less 

 than in residents at altitudes of 5000 feet and over. 



Observations were made upon myself at each locality (see Table III) ; 

 24 hours were allowed to elapse before the alveolar CO2 determinations were 

 made. My mean normal alveolar CO2 pressure at Oxford and at New York is 

 34 mm. of mercury (barometric pressures respectively 753 and 759 mm. of 

 mercury). The journey of about 33 hours to Highlands (altitude 3850 feet) 

 was made direct from New York, where the previous nine months had been 

 spent. At Highlands, a stay of over eight weeks was made. During the last 

 two and a half weeks I slept at a point about 400 feet higher than the 

 sanatorium, where work was conducted during the day, and through the 

 eighth week was more or less stationary at the higher altitude (4250 feet). 

 Contrary to the former experience at altitudes of 5000 feet and higher, the 

 alveolar C0 2 pressure did not fall, but remained, with slight variations, at the 

 normal value for sea-level (34 mm. of mercury;. In consequence, the alveolar 



* Ibid , p. 362. 

 + Ibid., p. 361. 

 X Ibid., p. 365. 



