Muscle and capsule temperatures during treatment were measured at two-minute intervals using National Bureau of Standards-Certified, thermometer-calibrated thermistors imbedded in 18 gauge hypo-dermic needles, in conjunction with a "read out" device (Yellow Springs Instrument Co Model 43 TD, Serial No 2466).** Corrections for depth immersion were applied, and the unimmersed portions of the needles were coated with Ddw-Corning RTV silicone to insulate against heat conduction. The thermistors' depth of penetration was calculated from radio-graphs. The positions of the needles were as follows: Experiment 1: Halfway between the wrist crest and the most prominent point of the metacarpopha-langeal joint of the thumb and 1.9 cm from the edge of the metacarpal bone. The depth of the probe under the skin surface was 0.43 cm; 1.35 cm of the needle was inserted