988 Summary and Conclusions 



a sudden consumption of oxygen, take from this blood, which is 

 already so poor, the insufficient supply intended for the nourish- 

 ment of the tissues, and reduce these tissues to poverty and im- 

 potency; but this discussion belongs rather in the study of the 

 symptoms of mountain travellers. 



First among extrinsic and unfavorable circumstances we must 

 mention the cold. Aeronauts have encountered extremely low tem- 

 peratures. Now, since the immortal works of Lavoisier, everyone 

 knows what super-activity in oxidations can be required for the 

 maintenance of a constant temperature. It is clear that in the 

 difficult conditions in which the source of oxygen, that is, the 

 arterial blood, is involved, the moment when the organism is 

 threatened can be hastened by the action of an intense cold. But 

 the patient must already, or nearly, have reached the phase of or- 

 ganic depression, without which the compensating action of the 

 same physiological means which permit us, at ground level, to 

 resist cold, would be able to work effectively in the upper strata. 

 A second dangerous circumstance is too great rapidity in the 

 ascent. However confused our ideas still are in regard to the 

 effects of habit, it is quite certain that modifications in our condi- 

 tions of life have much more painful consequences when they are 

 sudden than when they are brought on somewhat slowly; this fact 

 is very clear in the case of diminution of pressure, and we have 

 often seen in our experiments an animal suddenly overwhelmed 

 by a decompression to which we could have brought him easily 

 if we had made the transitions prudently; besides, this animal, if it 

 is not killed immediately, recovers more or less completely under 

 the same decompression which had almost been fatal to him. 



Up to now we have spoken only of the oxygen of the blood. 

 Can it be that the other gases, whose proportion diminishes 

 equally, play some part in the symptoms of decompression? Car- 

 bonic acid, whose diminution in the blood advances even more 

 rapidly than that of oxygen (See Fig. 31), does not seem to me 

 important in the case of aeronauts, who remain for so short a 

 time under the influence of decompression; we shall return to 

 that point when we speak of mountain dwellers. As for nitrogen, 

 it enters into the question only from the mechanical point of view. 

 We have shown the formidable part it plays in sudden decompres- 

 sions from several atmospheres on; but it seems to me impossible 

 to attribute the slightest unpleasant influence to its release during 

 even the most rapid balloon ascension: Coxwell and Glaisher took 

 50 minutes to arrive at an altitude of 8838 meters; Croce-Spinelli, 



