224 Historical 



On the other hand, since muscular energy in general is dimin- 

 ished, the lungs expand less, and compensation must be made by 

 greater frequency of inspirations. Then the editor of the Biblio- 

 thcque universelle adds: 



Clissold here suggests, without developing it, one of the causes to 

 which we should be tempted to attribute the greatest influence upon 

 one of the effects noted; we mean the expansion undergone by the air 

 enclosed in the abdominal cavity, as one rises in the atmosphere; this 

 expansion, by raising the diaphragm, lessens by so much the capacity 

 of the thoracic cavity, and does not permit the lungs to expand as 

 much as usual, until, by certain slow communications with the ex- 

 terior, equilibrium between the abdominal and thoracic cavities is 

 established again, and the latter regains its ordinary capacity. 



The French naturalist Roulin, 40 who spent several years fn Bo- 

 livia, in 1826 sent to Magendie a letter containing observations on 

 the pulse rate, made on the same persons at Guaduas (average 

 pressure 718 mm.) and at Santa-Fe-de-Bogota (560 mm.; 2643 

 meters above sea level) . They show a slight increase in the pulse 

 rate in the latter place. The difference is rather slight, and M. 

 Roulin concludes from this: 



According to that, we may assume that the effects felt when one 

 ascends lofty mountains and attributed entirely to the decrease of 

 pressure, when they are not due to cold or the fatigue of the ascent, 

 must be considered chiefly as nervous phenomena. 



And yet, a few pages farther on, the author adds: 



The difficulty in breathing which I felt on the plateau of Bogota 

 was at first attributed to the state of my health; but I observed that 

 several persons, who had recently arrived on the plateau, also com- 

 plained of this difficulty. 



It is evidently rather because of the name of their author than 

 because of their own importance that I have quoted these observa- 

 tions; they are anything but conclusive. 



It is also from the standpoint of curiosity that I report here 

 the conclusions from a work of John Davy 41 upon the gases of the 

 liquids and the solids of the body; it is a real step backward from 

 what Robert Boyle and Darwin had taught us. But the reader may 

 judge from that the hesitations between which the minds of physi- 

 ologists drifted. 



J. Davy carried out numerous experiments with the purpose of 

 finding out whether the liquids or the solids contain gases which 

 the pneumatic pump can extract. The results obtained were always 

 negative, and he concluded from that that there are no free gases 



