In the second place, when the injurious substances have to be wholly removed, the saliva plays the _rôle_ of a washing-out fluid; otherwise the material, by clinging to the mucous membrane of the mouth, might in longer or shorter time gain entry into the blood and there develop its noxious influence. This last function of the fluid is hardly taken into account at all in physiology, and yet it is evident that the saliva, as a cleansing fluid, must have a wide importance. If you only think of how often we are impelled to expectorate, that is, to wash out the mouth with saliva after something unpleasant, this will be clear. Such a view finds additional support when we reflect that a feeling of disgust produces almost as strong a flow of saliva as the sight of a tasty meal. In both cases the secretion performs the office of forerunner: in the first it prepares for the washing out of the mouth, in the second for the requisite elaboration of the food. Think how often, when something disagreeable enters the mouth, with what rapidity the saliva is poured out, even after the unpleasant substance has been for a considerable time removed, and not a trace more is apparent to the sense of taste. Indeed, long afterwards one has only to recall the circumstances to mind in order to bring on anew the secretion of saliva. Apparently the psychic excitation of the nerves of salivary secretion also ushers in the act of vomiting, which, as is well known, can be called forth by mental influence. Further, the function of the saliva just mentioned is probably the true physiological explanation of the feeling of disgust which many persons experience at the sight of the secretion itself. Hence I hold that substances which obtain entry to the mouth set up a secretion of saliva only because we have here the seat of a definite physiological sense, and not because the peripheral terminations of the buccal nerves are devoid of specific excitability, and capable of being thrown into action by every desired form of stimulus. In other words, the specific excitability of the peripheral endings of the salivary nerves is very comprehensive and widely extended. This is no picture of the imagination, for it can be supported by facts. To say nothing of the testimony of earlier authors, that the salivary glands have each particular exciting agencies to which they specially respond, we can demonstrate the following facts from the material collected in our laboratory.