642 Experiments 



Now, as M. Fernet remarks, since the respirable air contains only 

 one-fifth of oxygen, the proportion dissolved in the serum must be 

 diminished in the same proportion; whence it results that in the 

 blood the proportion chemically combined independent of the 

 pressure will be 3.3 x 5 = 16.5 times greater than that which follows 

 the changes of the barometric column. And therefore, he con- 

 cludes, "the absorption of oxygen is very nearly the same, whatever 

 the atmospheric pressure, on mountain tops and in the plains." 



To this conclusion, which considered only the quantity of oxy- 

 gen absorbed by an animal in a given time under different pres- 

 sures, and which agreed with facts previously noted by Regnault 

 and Reiset, Vierordt and Lehmann, the physiologists have added a 

 second, — which seems wholly justified, a priori, by the very re- 

 searches of M. Fernet, — namely, that in the blood of the living ani- 

 mal, the quantities of oxygen are almost independent of the baro- 

 metric pressure. "Otherwise," says Longet, 9 for example, "we 

 would reach this conclusion, that the blood of inhabitants of regions 

 where the atmospheric pressure is half the normal would contain 

 only half as much oxygen as the blood of those dwelling at sea 

 level, where the pressure is 0.760 meters. How can we believe that 

 observers would not have been struck by the profound modifica- 

 tions which such variations would not fail to produce in the manner 

 of existence of these populations?" 



This conclusion and the reasoning on which it is based were ac- 

 cepted by all the physiologists. It is very interesting to note that 

 when M. Jourdanet stated, basing his assertions on a long medical 

 practice, that in the lofty regions of the Mexican Republic, "the 

 mode of existence of the population is profoundly modified," the 

 very argument of Longet was turned against him, and the exact- 

 ness of his observations was denied as contrary to the data of 

 physiological chemistry. 



The explanation given by M. Jourdanet of the special patho- 

 logical state which he had noted on the plateaux of Anahuac was 

 entirely based upon the lessened absolute quantity of oxygen con- 

 tained by the blood of men and animals under so low a pressure. 

 Now we have just seen in the first subchapter that he was abso- 

 lutely right, and that, in spite of the natural astonishment of Longet. 

 it is correct to say that if one lowers the barometric pressure one 

 half, the oxygen content of the blood will be reduced almost one 

 half. 



There was then, between the result of M. Jourdanet's observa- 

 tions and our experiments on the one hand, and the logical conclu- 



