910 EDWARD C. SCHNEIDER 



Henderson (a) have shown, results in a reduction of blood alkali. While 

 after acclimatization the H-ions are again probably nearly the same as at 

 sea level, the restoration is never complete and in the end the stimulating 

 action of diminished oxygen leads to a greater ventilation of the lungs 

 than on the first day, and a permanent level is then established for that 

 barometric pressure. Haldane makes clear that if the initial alkalosis 

 should be maintained the dissociation of oxyhemoglobin would be less 

 than normal, thus accentuating oxygen want in the body. By restoring, 

 or nearly restoring, the H-ion concentration of the blood the curve of 

 oxyhemoglobin dissociation is again shifted back to or toward the normal 

 for sea-level. 



Metabolism. Investigations, in spite of an occasional positive finding, 

 lead to the opinion that metabolism is independent of the variations in 

 atmospheric pressure. Sundstroem found that the assimilative power for 

 the energy in the food remains normal at all altitudes. 



In 1883 Fraenkel and Geppert placed a fasting dog under the influ- 

 ence of diminished barometric pressure and found an increased protein 

 metabolism. Zuntz(a) and collaborators, on Monte Rosa at 2,900 m., failed 

 to show an increase in metabolism; but at 4,560 m., barometer 443 mm., 

 obtained an increase of approximately 15 per cent. Later Durig and 

 Zuntz, in an expedition to Teneriffe, altitude of 3,160 m., failed to show 

 an essential difference in metabolism. The Anglo-American expedition 

 to Pikes Peak found no difference in metabolism either during rest or 

 when taking exercise. Hasselbalch and Lindhard observed a man for 14 

 days in a pneumatic cabinet, at 455 mm. barometric pressure, and found 

 that the consumption of oxygen and the urinary ammonia and amino-acids 

 were unaffected. Sundstroem showed that the iron balance did not alter 

 nor the retention of iron exceed that observed in low altitudes. 



The diminished excretion of ammonia observed by Hasselbalch and 

 Lindhard and by Haldane and collaborators during the period when blood 

 alkalosis was being overcome has already been pointed out. Hasselbalch 

 and Lindhard found that an increased oxygen consumption might occur 

 during the process of acclimitization. Von Wendt(6) noticed a retention 

 of nitrogen, iron and potassium on Monte Rosa which he attributed to the 

 construction of new red corpuscles. 



The Circulatory Mechanism. Altitude, if great enough, increases the 

 heart rate; but it is generally recognized that at moderately high alti- 

 tudes, 6,000 to 8,000, or even 9,000 feet, there is no augmentation. 

 Shortly after ascending to such an altitude as 14,000 feet the heart rate 

 gradually increases during a period of several days. In persons who 

 develop "altitude sickness" and in those fatigued by climbing, the accelera- 

 tion begins sooner and is greater. With the development of acclimatiza- 

 tion the heart rate will return toward, and in some cases reach, the low 



