No taste sensation is evoked when distilled water is put on human tongue because man does not possess taste buds for tasting water. The taste buds present on the tongue send nerve impulses to the brain which actually preceives the taste sensation. Some mammals such as rhesus monkeys, pigs, cats and dogs possess some taste buds which send nerve impulses to the brain when distilled water is applied on them. It seems, therefore, that water may stimulate these taste buds to evoke taste sensation in these animals.