346 Historical 



The learned physician of Lyons seems to me no better inspired 

 when he ascribes to the diminished pressure the venous conges- 

 tions, because "the return of the blood to the right cavities of the 

 heart will be less active." His comparison of the heart to "a pump 

 operating in a medium in which the air is greatly rarefied, and 

 which could bring up water only from a much lessened depth" 

 (page 239) is not at all valid; no one believes now in the active, 

 sucking expansion of the heart. 



In conclusion, we shall quote a more accurate idea of the same 

 author in regard to the recall of the venous blood by pulmonary 

 expansion. One might think that the force of this recall should 

 be decreased by the decrease in pressure. And yet, when we think 

 it over, we see that there is no proof there: the return* of the 

 blood of the large venous trunks towards the heart takes place 

 because of the difference between the tension of the outer air 

 and that of the air which enters the lungs and expands there, since, 

 as we proved long ago, 5 in no animal can the opening of the glot- 

 tis suffice for the capacity of the respiratory pump. It would still 

 have to be demonstrated that this difference, the negative pressure 

 of the Germans, is less in rarefied air than in normal air, of which 

 we are by no means sure, and which is not even probable. 



Excess of carbonic acid in the blood. We have reported with 

 all the discussion it deserves the strange theory of M. Gavarret 

 (page 275) , explaining mountain sickness by a real poisoning by 

 carbonic acid. According to the learned professor, the act of as- 

 cent would require such an increase of organic combustion that 

 the carbonic acid which is the product of it could not be expelled 

 quickly enough, in spite of the increase in the number of respira- 

 tory movements and heart beats. The result would be a storing 

 up which brings symptoms of poisoning; and also the improve- 

 ment which immediately follows rest, during which the excess of 

 gas is expelled. 



This theory was accepted by M. Leroy de Mericourt, M. Aug. 

 Dumas, M. Scoutetten, M. Lortet (page 286), and many modern 

 authors. 



I do not dwell upon the difference between the symptoms of 

 mountain sickness and those of poisoning by carbonic acid. But 

 it is quite evident that the theory of M. Gavarret is open to the 

 same objection which we used in disproving the theories involving 

 fatigue and the theory of M. Lortet. It is clear, in fact, that the 

 quantity of carbonic acid which must be produced in raising the 

 body 1000 meters, for example, is independent of the altitude; so 



