In our experimental series, the lowest rectal temperatures which could be survived varied individually just as did the progress of the temperature drop. In general (in six cases) death occurred with a drop in temperature to values between 24.2° and 25.7° C. [75.6° and 77.6° F.]. In one case, however, a drop to 25.2° C. was survived. This experiment fell outside the typical picture insofar as after 90 minutes at 26.6° C. [79.9° F.] a virtually stationary condition of the rectal temperature had become established for 85 minutes. We will come back again to this special experiment. The _skin temperature_ sinks or drops much more rapidly than the rectal temperature. Within a minute there occurs a thorough saturation of the articles of clothing. Correspondingly the skin temperature falls already within 5 minutes to values between 24° and 19° C. [75° and 66° F.]. After 10 minutes it may have already dropped to 12° C. [54° F.]. Within 10 to 20 minutes more after the beginning of the experiment the steepness of the drop changes considerably. The curve of the skin temperature runs for some time, that is, for 15 to 30 minutes virtually horizontal. After this time there follows a further but now slower drop to the lowest figures, which may lie below 15° C. [59° F.] at the close of the experiment. Parallel experiments which compare the _course of the rectal temperatures_ and the cooling of the body with and _without submersion of neck and back of head_ showed great difference in temperature drop. The curves pertain to the same experimental subject. The one with the deep fall to 26° C. [79° F.] in 70 minutes was obtained with a water temperature of 12° C. [54° F.] the other with a drop to 32.5° C. [90.4° F.] in the same time resulted from a water temperature of 5.5° C. [41.9° F.]. The very marked difference cannot be explained by a variation in resistance of the particular person, but is to be attributed to the position of the subject in the water and his head covering. In the experiment with the water at 12° C. [54° F.] the subject, in a kapok life preserver, lay flat in the water so that his neck and the back of his head were well submerged; beyond this he did not wear a flier’s helmet. In the other experiment with water at 5.5° C. [41.9° F.] the head was covered with an aviator’s summer helmet without headphones. The subject wore a rubber life preserver open at the back; with this, the head is somewhat out of the water.