980 Summary and Conclusions 



when I analyzed the previous works of M. Jourdanet, I have given 

 his remarkable observations the place which they deserve; I cannot, 

 without repeating myself, return to them here. As to the hygienic 

 and medical considerations which my learned colleague has treated 

 with such length and interest, I can only refer the reader to this 

 book, which contains so many curious observations and new ideas, 

 so many proofs of profound and persistent learning, if I may use 

 the word "persistent", and guided by a theoretical idea which is 

 fortunate and fertile. He will wonder at the extent of the general 

 conclusions relative to the constitution of human races, to the 

 history of civilizations, and to philosophical politics, which M. 

 Jourdanet drew from this first observation, that, during a surgical 

 operation in Mexico, the blood which escaped from the arteries did 

 not present its usual reddish hue (vol. I, p. 171). But I cannot 

 continue longer here. 



Subchapter II 

 SUMMARY AND PRACTICAL APPLICATIONS 



We have given, in our second part, with a superabundance which 

 may perhaps have appeared excessive, the proofs of this truth that 

 diminution in the barometric pressure acts on living beings only 

 by diminishing the tension of the oxygen which they breathe, and 

 if things are carried to the extreme, by asphyxiating them for lack 

 of oxygen. Also that there exists a parallelism to the smallest 

 details between two animals, one of which is subjected in normal 

 air to a progressive diminution of pressure to the point of death, 

 while the other breathes, also to the point of death, under normal 

 pressure, an air that grows weaker and weaker in oxygen. Botli 

 will die after having presented the same symptoms; and at different 

 moments of the experiment, at death even, one can observe in 

 both the same proportion between the oxygen tension in the outer 

 air and its proportion in their blood. 



All the old theories about the mechanical action of decompres- 

 sion should have disappeared entirely, and it really should be 

 enough to show their folly to recall the experiment in which I 

 went down to the fatal pressure of 248 mm. without the least in- 

 convenience, under the single condition of restoring the oxygen 

 tension to its normal degree by breathing an artificial super- 

 oxygenated air. 



