only the usual pains attendant with bends occurred. In a further experiment with a stay of 40 minutes duration at an altitude of between 13 [42,650 ft.] and 13.5 km. [44,290 ft.] there developed very gradually a condition of weakness, combined with a peculiar headache, which then led to a considerable slackening of strength in the arms and hands. As a result of this, Ro. could no longer hold the breathing mouthpiece (for special reasons in these experiments, Ro. had to breathe with a mouthpiece and nose clamp) so that it slid out of his mouth. All these phenomena were still clearly observed by Ro. Ra. returned the mouthpiece to Ro. However at this point Ro. failed rather suddenly with paleness, strong cyanosis of the lips and complete unconsciousness. After Ro. had regained clear consciousness through descent and sufficient O_{2} breathing, he determined the existence in himself of a complete paralysis of the legs, weakness of the arms and severe disturbances of vision. These serious disturbances developed although the time of oxygen lack and unconsciousness had lasted only about 5 seconds. Following descent soon after this to 0 km., the paralysis of the legs continued for about 5 minutes more and the very severe visual disturbances only cleared up after 2 hours. While this episode of Ro.’s occurred in an experiment at a special altitude, the disturbances occurred in Ra. at an altitude of between 12 [39,400 ft.] and 13 km. [42,700 ft.] while he was breathing sufficient oxygen with a mask and continuous flow into the circuit. After 10 minutes stay at this altitude, pains began on the right side with a spastic paralytic condition of the right leg which increased continually as though Ra.’s whole right side were being crushed between two presses. At the same time there were most severe headaches as though the skull were being burst apart. The pains became continually more severe so that at last the discontinuation of the experiment became necessary. The pains disappeared when ground level was reached while the disturbances of the right leg continued about 5 minutes more. Shortly before the [page 18 of original] second experiment, Ra. took two tablets of “Antineuralgica” (a coal tar derivative) and two tablets of pervitin. In the course of the experiments there occurred only light pains in the right arm and leg, moderate headaches, but a very severe uncontrollable urge to cough, actually less severe difficulties than in the foregoing experiment, although this one was made at 1,000 m. [3,280 ft.] higher. Ro. experienced disturbances which in quality resembled the severe disturbances in the 15 km. [49,200 ft.] sinking experiment, although the degree of oxygen lack in this experiment was negligible in comparison to the 15 km. [49,200 ft.] experiment, so that the idea of a combination of pressure drop phenomena with the phenomena of oxygen lack is definitely suggested. _2. Descending experiments with O_{2} breathing_