Theories and Experiments 281 



of compressed air, although the causes are opposite. Whereas in com- 

 pressed air there is a deeper inspiration spontaneously, as a mechani- 

 cal effect of the increase in pressure, it is, on the contrary, the need 

 of getting air, which, since it cannot be satisfied in rarefied air by 

 normal inspirations, necessarily produces deep and forced inspirations. 

 One experiences at the same time a feeling of uneasiness, oppression, 

 during which the inspiration is especially difficult, because, even in 

 atmospheric air, it requires more energy than the expiration, whereas 

 the latter, in rarefied air, is made more easily and more quickly. 

 (P. 16.) 



Vivenot also made observations on the pulse rate. It rose from 

 78 to 80 in Dr. M., from 73 to 82 in Dr. L., from 61 to 76 in M. de G., 

 from 80 to 105 in Vivenot himself. 



A veterinarian of the Royal Corps of English Engineers, Fleme- 

 ing, 118 published in 1867 a work in which he reports a fairly large 

 number of travellers' observations, and at the head of which he 

 expresses his theoretical opinion about the effect of decompres- 

 sion: 



If the pressure is reduced artificially, as when one climbs a moun- 

 tain or ascends in a balloon, one notes the same phenomena as in 

 fish taken from the water. 



The body swells, the inner fluids distend the tissues outwards, 

 exerting a vigorous pressure on them, burst the vessels, and often 

 cause hemorrhages. 



Rarefied air contains less oxygen in a given volume, so that 

 respiration, being incomplete, is accelerated to compensate for this 

 deficiency; the inspirations are proportionately more numerous; the 

 heart contracts vigorously and more frequently, the blood circulates 

 with difficulty, the lungs are congested, the blood vessels are dis- 

 tended, and aneurisms are formed. (P. 9.) 



In summary, according to Flemeing, the effect of altitude can 

 be produced in several ways: 



1. By the decrease of the atmospheric pressure: the muscles and 

 the articulations tend to relax, the blood stops or transudes through 

 the walls of the vessels, especially the mucous membrane of the air 

 passages, the lungs, and the brain envelopes. 



2. By cutaneous and pulmonary evaporation .... 



3. The frequency of the circulation and the respiration is coun- 

 terbalanced, or better, caused by the small quantities of oxygen which 

 the inspired air contains. 



4. The lowered temperature .... 



5. The more powerful rays of the sun ... . which cause irrita- 

 tion of the eyes, the brain, and the spinal cord. (P. 12.) 



M. Bouchard, in his noteworthy thesis .on the pathogeny of 

 hemorrhages, 110 is led to express his opinion about the cause of 

 the symptoms, noted both in persons subjected to a considerable 



