These experiments proved that from 14 kilometers on down severest bends occurred which remained until the ground was reached. The detrimental effects caused by these experiments manifested themselves at the beginning as unconsciousness, and subsequently as spastic and limp paralysis, catotomy, stereotypy, and as retrograde amnesia lasting several hours. About 1 hour after the end of the experiment the VP’s for the most part were still disoriented as to time and locality. The blood picture often showed a shift to the left; albumen and red and white blood corpuscles were regularly found in the urine after the experiment; cylinders were sometimes found. After several hours or days the blood and urine returned to normal. The changes of the electrocardiograph were reversible. Contrary to descending tests on parachutes without oxygen, descending tests with oxygen were carried out from heights up to 18 kilometers. It was proved that on the average the VP’s regained the normal function of their senses at 12 to 13 kilometers. No disturbances of general conditions occurred during any of these experiments. Brief unconsciousness at the beginning of the experiment caused no lasting disturbances. Urine and blood showed only a slight change. 4. As the long time of descent on parachutes, under actual conditions, would cause severe freezing even if no detrimental effects were caused by lack of oxygen, VP’s were brought by sudden decreases in pressure with a cutting torch from 8 to 20 kilometers, simulating the damage to the pressure-machine of the high-altitude airplane. After a waiting period of 10 seconds, corresponding to stepping out of the machine, the VP’s were made to fall from this height with oxygen to a height where breathing is possible. The VP’s awoke between 10 and 12 kilometers and at about 8 kilometers pulled the parachute lever. 5. In experiments of falling from the same height without oxygen, the VP’s regained normal function of their senses only between 2 and 5 kilometers. 6. Experiments testing the effect of pervitin on the organism during parachute jumps, proved that the severe after-effects, as mentioned under No. 3, were considerably milder. The ability to withstand the conditions at high altitudes was only slightly improved, while the bends, since they were not noticed, occurred suddenly (restraint-loosening effects of pervitin).