The daily water intake of adult Brown Leghorn hens was measured at water temperatures of 0, 10, 20, 30, 40 and 45 degrees C. The electrical activity of neurones in the nucleus ventro-lateralis anterior solitarii (NVLAS) of the medulla was also measured when the mouth was stimulated with water at the same temperatures. 2. There was a significant decrease in water intake when the temperature of the water was 10 or 45 degrees C. 3. There was an increase in activity of some of the NVLAS neurones with decreasing water temperature and this activity was in response to specific "cold" receptors. 4. Some NVLAS neurones were identified which showed an increase in activity at temperatures of 45 degrees C and more; it was concluded that these represented responses to thermal pain. 5. It is concluded that the effects of temperature on water intake may in part be explained by the behaviour of the oral receptors.
