Summary and Discussion 317 



is severely attacked seems a little higher than in the Alps; on the 

 volcanoes of the Pacific, which exceed 4000 meters, the sickness is 

 hardly worse than on the Peak of Teneriffe; the same thing is true 

 of the Kamerun Mountains, and on Kilimandjaro, New reached 

 an altitude of about 5000 meters without serious distress; in North 

 America, Fremont and his companions were ill at about 3500 

 meters; but in Mexico one must mount above 4500 meters, to expe- 

 rience perceptible discomforts; they are not always very serious 

 even on the summit of Popocatepetl (5420 meters). The long 

 mountain chain of South America cannot be crossed at any point 

 from Chile to Colombia without inflicting the terrible puna upon 

 most of the travellers. But it seems that these sufferings do not 

 appear at a completely uniform height; whereas on the passes of 

 Santiago in Chile many are sick below 4000 meters, and almost 

 all foreigners are severely attacked at La Paz (3720 meters), and 

 even at Chuquisaca (2845 meters), and all at Cerro de Pasco 

 (4350 meters), the ascent of the mountains near Quito causes 

 almost no symptoms up to 5000 meters, and a thousand meters 

 more present no unsurmountable difficulties from the physiological 

 point of view. 



The immense mountains of central Asia may be compared to 

 the Andes of Upper Peru from the standpoint of the line where 

 mountain sickness appears. Passes less than 4500 meters high are 

 crossed without serious sufferings; there are some more than 5500 

 meters high which are considerably frequented; several travellers 

 have reached,' 6000 meters, and the Schlagintweit brothers 

 ascended to the prodigious height of 6882 meters on the sides of 

 Ibi-Gamin. 



These inequalities, from our standpoint, among the different 

 mountainous regions of the earth, stand out among the multitude 

 of facts which we have listed; but one can easily find numerous 

 exceptions to these general rules. Indeed, and this is not the least 

 interesting fact revealed to us by these multiple observations, we 

 see that in the same region of the earth, in the same mountain 

 chain, certain definite places are particularly feared by travellers 

 and natives; and these places are not always the highest, far from 

 it. This peculiarity is noted even in the ascent of a given moun- 

 tain; for instance, the Couloir of Mont Blanc, where symptoms 

 often appear which disappear on the summit. In a word, and these 

 facts have been noted particularly in the Andes and the Himalayas, 

 the intensity of the symptoms is not always in proportion to the 

 altitude reached. This was the origin of strange hypotheses imag- 

 ined by the natives, to which travellers too often gave credence; 



