Decreased Pressure 999 



tance; not only does it introduce a greater quantity of air into the 

 lungs in a given time, but this air is distributed better and more 

 usefully in the respiratory tree. M. Grehant - r ' shows that, although 

 the coefficient of ventilation is 0.060 for inspirations of 300 cc, it 

 becomes 0.159 for inspirations of 600 cc, that is, much more than 

 double for double inspirations. So, he says, and this is not the least 

 interesting among the results of his fine studies: "Thirty-six in- 

 spirations of 300 cc. made in one minute (10.8 liters) will not 

 renew the gases of the lungs as well as 18 inspirations of a half- 

 liter each (9 liters) p. 537)." That is a consideration which we 

 have not taken into account till now. 



The circulatory apparatus also comes to the rescue. M. Mer- 

 mod (p. 330) found that his pulse rate rose from 62 to 66, then to 

 68, living successively at 300, 600, 1100 meters of altitude. Now, as 

 we have said, the greater rapidity of the irrigation of the tissues 

 by the blood should on one hand compensate for the slight deficit 

 of oxygen, and on the other, diminish, by a sort of washing, the 

 proportion of organic wastes retained in the tissues. 



Finally, the foreign volatile substances should disappear from 

 the blood, and the carbonic acid lessen there; this decrease is 

 slight, of course, since at 1500 meters (63 cm.) it should be about 3 

 volumes out of 40 (See Figure 31), supposing that all other con- 

 ditions are equal; but no one can state that it is absolutely unim- 

 portant, and we may think that it is, on the contrary, favorable to 

 the energy of the vital faculties. First, such a diminution takes 

 place in the venous blood (See Figure 40) , and consequently in the 

 tissues on which, as I have shown, this acid acts as an anesthetic. 

 We know, furthermore, that the functioning of the muscular and 

 nervous systems results in the formation of lactic acid, and that 

 the accumulation of this acid is very dangerous to the soundness 

 of the organic functions. Now we have seen that the arterial blood 

 almost never contains any dissolved COo, and that almost always, 

 on the contrary, its bases are not absolutely saturated with car- 

 bonic acid. If then the alkalinity of the blood increases, the effects 

 of the formation of lactic acid can more easily be compensated for, 

 and a feeling of better health may be the consequence. 



Let us add that these changes in abode, generally planned for 

 reasons of health or pleasure, take the traveller from customary bad 

 conditions of life, subject him to baths of air, to exercise, to more 

 strengthening diet, make digestion easier, compel him to rest his 

 nerves, and stir his blood with the sight of the splendors of nature. 



