Theories and Experiments 263 



The second letter'' 7 treats of "acclimatization on the heights 

 of Mexico"; it contains only a summarizing description of the races 

 of Mexico and a little meteorological information. However, I 

 quote the following passage, which is rather interesting: 



After crossing Cumbre, when we reached an elevation above 2000 

 meters, first respiration and circulation, and afterwards absorption, 

 exhalation, and metabolism underwent noticeable changes. We per- 

 ceived a tendency of the fluids of the body to move towards the 

 periphery, the result of which was derangement of the circulation, 

 various congestions, cerebral, pulmonary, and nasal hemorrhages, 

 several examples of which I have given; difficulty in breathing, which 

 made us pant; general discomfort, which made us consider the weather 

 heavy, although it was really lighter; difficulty in moving and greater 

 fatigue, and these symptoms were particularly marked in the men of 

 the 95th of the line, who had not remained long at Orizaba, like us, 

 and who had been transferred rather suddenly from sea level to a 

 fairly high elevation. Little by little, the organism of everyone, at first 

 in conflict with a medium for which it had not been created, adapted 

 itself progressively to this medium, and today, after a ten month 

 sojourn on Anahuac, it has been so transformed that it resembles that 

 of the Indian. (P. 817.) 



The third letter 98 is much more important to us. In it is the 

 report of the analyses made in the laboratory of the School of 

 Mines of Mexico under the supervision of Professor Murfi, with 

 the purpose of measuring the quantity of carbonic acid formed in 

 a given time by dwellers on the lofty plateaux. Twenty-five per- 

 sons, 10 of whom were French, 10 Indians or half-breeds, and 5 

 Mexicans of European origin, were the subjects. The average re- 

 sults, for the French, for example, are given in the following table: 



Number of inspirations per minute 19.6 



Pulse rate 78.2 



Quantity of air expired in one minute 5.90 liters 



Average percentage of carbonic acid per minute 4.24 



If we set aside the discussion which Coindet gives about the 

 petty differences of details noted among the representatives of the 

 different races on whom he experimented, we find that these 

 observations inspired the following reflections in him: 



The average quantity of air expired per minute according to M. 

 Dumas is 5.3 liters at sea level; here generally we have about 6 liters, 

 when once the man is acclimated. This is logical, for since the air 

 of altitudes contains in a given volume less oxygen at a barometric 

 pressure of 0.58 or 0.59 meters than at 0.76 meters a greater quantity of 

 this air must be absorbed to compensate for the difference: this is at- 

 tained by a more active respiration; so that the air which is drawn into 



