246 



THE HUMAJN MOTOR 



millions 



7.25 

 7.00 

 6.75 

 6.50 

 6.25 

 6.00 

 5.75 

 5.50 

 5.25 

 5.00 

 4.75 

 A-.50 



z 



Julv 



AA 



Sepi 



Nov 



)an 



Msr 



7.25 

 7.00 

 6.75 



6.00 

 5.75 



to 



Fio. 140. 



Effect of altitude on the richness of the blood in red corpuscles. 



The relative independence of the inter-organic oxydizations of 

 the atmospheric pressure is an experimental fact of great im- 

 portance ; life, which is combustion, is not therefore seriously 

 affected by the oscillations of the barometer. But it goes without 

 saying that to consume the same amount of oxygen, the ventila- 

 tion must needs be greater and the respiratory labour more in- 

 tense. This is probably why Zuntz and Dung, in their ascent of 

 the Tylde Peak (3,700 metres) at Teneriffe, found that, whether 

 resting or working, the expenditure of oxygen was greater at 

 the summit than at the foot of the mountain. ( l ) Mosso ( 2 ) found 

 on Mount Rose, at a height of 4,500 metres, equivalent to a pres- 

 sure of 428 millimetres, that the pulsations and the respirations 

 were modified, and that the vital capacity was subject to slight 

 decrease. By taking an ergographic tracing of the fatigue, irre- 

 gularities were revealed which seem to show that at a height 

 the nervous system does not function so well as regards its motor 

 centres. In the case of a man having to produce a moderately 

 large amount of mechanical work at any considerable altitude, 

 it is obvious that the respiratory activity will be troublesome. ( 3 ) 

 The expired gases are seen to be relatively rich in carbonic gas 

 and poor in oxygen ; in contrast, the blood is poorer in carbonic 

 gas the higher one climbs ; there is, to use Mosso's word, a tend- 

 ency to acapnie ( 4 ) x aTCO ?> smoke). The nervous centres, irri- 

 gated by acapnie blood, exhibit the irregularities of action, which 

 we have pointed out. 



(*) Jean Mascart (Rev. Gin. Sciences, 1910, p. 633). 



() A. Mosso, (Fisiologia del Uomo sulle Alpi, 1897, Milano, pp. 7, 11, 37-46). 

 ( 8 ) L. Hill (Nature, vol. Ixxxiv., 1910). 



( 4 ) A. Mosso (Arch. Ital. Biol., 1901) ; Haldane (Proceed. Roy. Soc. t 

 18th Jan., 1912). 



