MOUNTAIN SICKNESS 215 



Plants cultivated on mountains become coriaceous and spinous 

 like desert plants ; there is an hypertrophy of the roots and an atrophy 

 of the parts above ground. The cells of the leaves thicken, the palis- 

 sade tissue hypertrophies, and the chlorophyll becomes very abundant. 

 These changes resist the increased evaporation and compensate for the 

 diminished tension of CO. 7 . 



At 410 mm. Hg ordinary plants wither up however wet the 

 earth is kept. At 500 mm. Hg germinating cress seeds grow half 

 as quickly as at 760 mm. Hg, while at 70 mm. Hg they refuse to 

 germinate. In the Alps the forests end at 1800 m. ; in the Andes 

 the vine grows even at 3000 m. ; in the Himalayas the apricot at 

 3000 m., and the poplar at 4000 m. 



MOUNTAIN SICKNESS 



The travellers who followed the conquerors of South America 

 first recorded the peculiar effects of high altitudes. Neither in 

 the history of Cortez, the conqueror of Mexico, who sent an 

 expedition up the crater of Popocatepetl (5420 m.), nor in that 

 of Pizarro, who with 62 horse and 102 foot soldiers penetrated 

 the Andes to the heart of the empire of the Incas, is there 

 any definite chronicle of this sickness among the general record 

 of suffering from cold and hunger. 



A Jesuit, Acosta, gave in 1590 the first clear description of 

 the symptoms of mountain sickness. These symptoms are short- 

 ness of breath, palpitation of the heart, nausea, loss of appetite, 

 injection of and bleeding from the mucous membranes, vertigo, 

 faintness, and in particular the difficulty of making any muscular 

 exertion. Many are affected at 2000-3000 m., every one suffers 

 at 4000 m. from shortness of breath and fatigue, while more 

 serious symptoms generally occur at 5000 m. Training and 

 acclimatisation have a great influence. At Quito and Potosi 

 girls dance half the night and toreadors display their skill in the 

 bull-ring, while de Saussure and his companions were so over- 

 come at their first ascent of Mont Blanc that every movement 

 became a difficulty. So is it with new-comers at Potosi. 



Conway, when out of training for hill-climbing, suffered from 

 shortness of breath at 7000 ft. in the Alps, a symptom which 

 he had not experienced, when trained, at 19,000 ft. in the 

 Karakorams. While building the Matterhorn hut at 4114 m. 



