Theories and Experiments 295 



always very sure of the superiority of ''the more scientific ex- 

 planation". 



Henderson 135 also speaks of plants; only it is not a kind of 

 moss, but an artemisia: 



Before reaching camp, many of our followers complained of head- 

 ache, and I found several of the Thibetan shepherds lying by the road, 

 in a state of complete prostration. When I asked them what was the 

 matter, they placed one hand on their foreheads, and with the other 

 tore up a piece of a strong-smelling artemisia, making signs that this 

 plant was the cause of their sufferings. On several of the passes, this 

 artemisia has an extremely powerful odor, and all the baggage, the 

 horses and the men coming from Yarkand are tainted with it. Even 

 mutton has this odor. 



Drew 1:; " does not limit himself to mentioning this prejudice 

 and refuting it authoritatively, he looks at the question itself, and 

 does not inquire why one is sick, which seems to him very simple, 

 but how one can resist the dangerous effect of expanded air: 



In the valleys of Rupsku, water boils at about 187°' F., which 

 corresponds to a barometric elevation of 17.8 inches; so that the quan- 

 tity of air — and oxygen — drawn into our lungs by an ordinary inspira- 

 tion is only 7/12 of the amount that enters at sea level. How do the 

 Champas (tribes which occupy the high plains of Rupsku, to the south- 

 east) compensate for this loss? I cannot tell exactly; I think, first, 

 that there is less wear and tear on the tissues in their bodies than in 

 the tribes which live in lower and warmer regions; they take less 

 muscular exercise than the peoples of the surrounding lands; it is true 

 that they are good walkers, but they think little of this quality and do 

 not wish to carry burdens. Watching over flocks is not an occupation 

 which causes the muscles to act vigorously. But that cannot explain 

 everything; there must be some compensating habit which makes them 

 capable of absorbing a large volume of this rarified air; probably, with- 

 out realizing it, they breathe more deeply. 



In us, this oxygen compensation tends to take place by a simple 

 and direct means. Respiration becomes more rapid and more deep; 

 there is an effort to increase both the number of inspirations and the 

 capacity of each of them. The intensity of this effect increases every 

 time one mounts a little when one is already above the level where 

 ordinary respiration is sufficient. (P. 290.) 



The natives commonly attribute these harmful effects of rarified air 

 to plants which, in their opinion, have the power of poisoning the air. 

 Some of the plants which grow at high altitudes exhale an odor when 

 they are crushed, and it is to them that the discomforts are attributed. 

 The onion, so much abused, which grows wild at great heights, is often 

 blamed. But an easy reply to this error is that the effects are most 

 marked at elevations where these plants, and all other vegetation have 

 disappeared. (P. 292.) 



