28 Historical 



spoken; it is the Mareo of the Puna; and it is rare that they are not 

 attacked by it. It is a disease quite like that which one feels at sea: 

 it displays all the symptoms of it and follows the same course. The 

 head whirls; one feels very hot; and painful nausea comes on, followed 

 by bilious vomiting. Strength fails, the body weakens, fever appears; 

 and the only comfort one finds is in vomiting. Some people are even 

 so weakened that they would cause anxiety, if it were not certain that 

 the -trouble was nothing but this Mareo. That lasts usually one or two 

 days, after which health is restored. This inconvenience is greater or 

 less according to the natural constitution of the person; but few escape. 

 When anyone has felt it once, it is extraordinary that he should be 

 attacked by it again in passing by Puna or coming from low countries 

 or any country in which there is a high temperature (page 116). . . . 



There is also observed in these climates another symptom to which 

 animals are subject. As soon as they pass from the plains to these 

 eminences or Punas, as from countries where there are dwellings to 

 the summits which surround them, breathing becomes so difficult for 

 them, that in spite of the different pauses they make to get their breath, 

 they fall and die there (page 118). 



Ulloa then discusses the different explanations suggested in his 

 time to account for these phenomena, and energetically rejects the 

 idea of toxic emanations due to minerals buried in the earth, an 

 idea which is current even today among the common people and 

 even in the educated classes of Bolivia and Chile. Then he adds: 



The men who have recently come to this climate also experience 

 something similar to what I said about animals; while walking, they 

 feel a suffocating and very painful fatigue, which forces them to rest a 

 long time; that happens to them even in the flat lands; now there can 

 be no other cause for this phenomenon than the keenness of the air; 

 but as the lungs become accustomed to this atmosphere, the discomfort 

 lessens. However, they still experience some difficulty in breathing 

 when they wish to climb some slope; this is inevitable, but is not felt 

 in other countries where the atmosphere has a regular density. 



This lightness of the air is favorable to those who have become 

 asthmatic in a denser air. This asthma is known by the name of 

 ahogos or suffocation; it is rather common there; that is why those who 

 are attacked by it in the low countries go up into the mountains; al- 

 though they do not entirely recover there, they live there nevertheless 

 without pain: on the contrary, those who became so in high altitudes 

 are well in the lowlands; so change of air is a certain alleviation in this 

 sort of disease. The science of medicine might profit by these experi- 

 ences, sending the patients of one country into another, although 

 elsewhere there is not so great a difference of altitude. 



Difficulty of breathing is noted also to a certain degree in the high- 

 lands of the province of Quito, but it is less painful there: no doubt 

 that is because one of these countries is on the equator, or nearly so, 

 whereas the other is remote from it. The conclusion is that the Punas 

 or summits of Peru are less cold and the air less cutting than in the 



