1. Experimental evidence is furnished to show that in normal animals the rectal temperature can be elevated by the passage of high frequency currents.
2. During life the intraabdominal and intrathoracic temperatures can be increased only slightly above the rectal temperature.
3. The lung temperature in the anesthetized dog normally lies 0.3–0.4°C. below the rectal temperature. During the passage of diathermy currents of strengths equivalent to those used in therapy this relationship is reversed—the lung temperature exceeding the rectal temperature by about the same value.
4. Immediately after death, the temperature rises abruptly in the deep tissues between the electrodes.
5. For the measurement of deep temperature special thermocouples have been devised. Their method of preparation and mode of use are described.