Records of the hallucinations of sane and insane people also show taste to play a relatively minor rôle, so far, at least, as frequency of report is concerned. In both cases visual, auditory, tactile, and olfactory hallucinations seem to be more common experiences. “Subjective tastes,” or tastes which do not appear to be caused by the action of any substance in the mouth, are, however, by no means unknown, although in most cases it is apparent that these tastes come from some unsuspected irritation of the taste organs by actual agents. Substances circulating in the blood may often be seen to be responsible for these “subjective tastes.” Thus, in diabetes the excess of sugar in the blood may give rise to a persistent sweet taste, and in case of jaundice biliary products often produce sensations of bitter. Various drugs, when present in the blood stream, also provoke well-known effects in taste, and it is quite probable that the taste hallucinations associated with nervous and mental disorder have their origin in some abnormal irritation of the nerves or brain centers involved in taste. Distilled water, which is presumably as tasteless a substance as could be found, is reported as tasteless by only about 50 per cent of observers. About 25 per cent report it as having a bitter taste, while certain cases are found in which it tastes sweet, or salt, or sour, or as having some unknown taste. As the result of careful study of these facts, Brown suggests that “we may perhaps infer that the ‘taste’ of water is not, after all, a taste quality, but is due rather to the presence or absence of some tactual characteristic; the absence, perhaps, of the ‘bite’ which is associated with sweet, salt, and sour alike.” It is also possible that mechanical stimulation of the taste organs can produce true taste qualities, just as mechanical stimulation of the retina produces spots of light and the tapping of a “warm spot” may produce a faint sensation of warmth. ------------------------------------------------------------------------ CHAPTER XII UNUSUAL AND ABNORMAL TASTE EXPERIENCES _Gustatory Hallucinations and Auræ_