CHANGES IN RESPIRATION 603 



up to an elevation of 3000 metres (Colle cTOlen) ; at a 

 height of 4500 metres at the Margherita cottage, however, 

 an increased pulse frequency manifested itself from the day 

 of the ascent on, in all the members of the expedition, which 

 gradually diminished somewhat, but did not fall to the 

 normally observed rate even in the course of a month, and 

 proved to be independent of any passing rise of temperature ; 

 then, too, the pulse rate was persistently very changeable. 

 After returning into the valley this variability not only 

 disappeared at once, but the pulse rate fell even below 

 normal. Apparently we should attribute symptoms of this 

 character to an abnormality in the function of the vagi. 

 The form of the pulse curve, and, too, the blood pressure 

 showed no typical changes, at least wherever no overexer- 

 iton had taken place. 



Changes of Respiration. The study of the changes in 

 the respiratory activity occupies a very large field in the 

 physiological literature upon alpinism, as might be sup- 

 posed. 56 The economy has a tendency to compensate for 

 the reduction in the partial pressure of oxygen by an in- 

 crease of ventilation ; thus in a very large majority of cases 

 it may be observed at high elevations that the depth of 

 breathing increases. Apparently the organism can also 

 protect itself against a decrease in the atmospheric oxygen 

 by a relative increase of the amount of oxygen absorbed, 

 and too by an acceleration of the circulation of the blood. 57 

 Increase in the depth of breathing has, it is true, been noted 

 by A. Lowy and F. Miiller also at the seashore. On the 

 other hand, according to Durig, a distinct increase of ven- 

 tilation effort begins to be noticeable only from altitudes of 

 3000 metres and upwards. However, no basic type of 

 adaptation of the respiratory mechanism can be distin- 



68 Literature: J. S. Haldane and E. P. Poulton (Physiol. Lab., Oxford), 

 Jour, of Physiol., 37, 390, 1908; R. 0. Ward, ibid., 378; J. Barcroft (Physiol. 

 Inst., Cambridge), Jour, of Physiol., 42, 44, 1911. 



OT Cf. J. Tissot, Jour, de Physiol, 12, 492, 520, 1910. 



