The effects of soaking the skin in water at various temperatures on the subsequent ability to sweat.

1. The ability of two human subjects to produce sweat was measured before and after immersion for up to 4 hr in water at 32-36 degrees C (soak).2. The ability to produce sweat declined about 4 times as rapidly when the subject was soaked at 36 degrees C as at 32 degrees C.3. The rate of decline characteristic of soaking at 36 degrees C was shown by subjects exercising in water at 35 degrees C, but not at rest at 35 degrees C. The difference appeared to be related to the presence or absence of moderate sweating (300 g/hr) during the soak. At higher rates there was no further increase in the rate of decline.4. Soaking at 39 degrees C for 5 min, after which the water temperature was reduced to 33 degrees C, caused a decline consistent with the supposition that while the subject was sweating the rate of decline was the same as that at 36 degrees C and for the rest of the time the same as that at 32 degrees C.5. It is concluded that the rate of decline is increased if the sweat ducts are perfused, and some possible mechanisms are discussed.