The bradycardia at a body temperature of about 29° to 30° C. [84° to 86° F.] changed suddenly to an _arrythmia perpetua_ or, as the case may be, to a _total irregularity_ and this began with a slow form of about 50 beats per minute; this slow form of irregularity could be transformed into a faster one. The transformation to the faster form was not an unfavorable sign regarding life. When an electrocardiographic control after the experiment was possible, it regularly showed a Vorhof flutter. Let it be anticipated _that this irregularity could continue to exist after the cessation of the cooling and a recovery of the body temperature to 33° or 34° C. [91° or 93° F.] 1½ to 2 hours after removal from the water_, but then customarily changed of itself and without therapeutic aids into a coordinated heart activity. In the same way let it be anticipated that in all cases with a lethal termination, a sudden cessation of the heartbeat ensued upon an irregularity of the slow type. A check of the _blood pressure_ was attempted, but was in no case satisfactory since an exact measurement was not possible in the decisive stage of the experiment because of the severe rigor and muscle fibrillation. Reference has already been made to _individual differences in the behavior of the rectal temperatures_. Figure 4 gives an example which includes four experiments, in which four different experimental subjects were cooled at identical water temperatures and with identical clothing. It was shown that in water at 4.5° C. [40° F.] temperature the time required for reaching a rectal temperature of about 29.5° C. [85° F.] varies between 70 and 90 minutes. But nevertheless the diagram shows that in spite of these individual differences, it is observable that the progress of the rectal temperature proceeds according to rule. The body temperature begins to sink rapidly from about 35° C. [95°-97° F.]. _It is of very great practical significance at this point that the body temperature continues to sink virtually lineally for a considerable time after removal from the water._ This continued drop can last 20 minutes or more. During this drop an after-drop of 4° C. [7° F.] could be observed, and indeed not only at temperatures under 30° C. [86° F.]. In one case it was observed that an interruption of the experiment at 35° C. [95° F.] after a further lapse of 20 minutes the rectal temperature had fallen 4° to 5° C. [8° F.] more. We will later discuss the “arresting” of this after-drop by physical measures.