The effect of altitude upon various nervous functions.

explained by the reduced alkali reserve that is characteristic of the acclimatized state, but must be due to an increased sensitivity of the respiratory centre to carbon dioxide. The above results have some bearing on practical mountaineering. I t is clear that if oxygen equipment is used for mountain climbing, ventilation will be least at any level of work in the unacclimatized man. As soon as acclimatization has occurred, the ‘ fixed ’ hyperventilation will persist even if pure oxygen is inspired and will consequently call for an increased volume of inspirate. Also, the diminished alkali reserve which is a secondary result of the hyperventilation will diminish the C0 2 transport capacity of the blood which then may become the factor limiting climbing rate. However, if an unacclimatized climber went directly from sea level to the top of Everest, he would be in great danger if his oxygen equipment broke down at altitudes above 20000 ft.