1. The demand for oxygen-carrying elements of the blood increases directly with the altitude. 2. In normal individuals this requirement is met through an increase in the red blood corpuscles and hemoglobin in from three to five weeks-the normal acclimatization. 3. This power of adaptation is diminished or want¬ ing in certain individuals. 4. Deficient acclimatization results in oxygen want or relative anemia. 5. As a result of diminished or limited oxygen sup¬