1. We may take taste and smell together. This last sense is much more extensive, much richer and more varied than the other; common speech often confounds them, enriching taste at the expense of smell. Although unscientific, this confusion does not greatly concern us. Every one knows that professional tasters, cooks, certain chemists and perfumers, can distinguish the most delicate gradations and correctly identify them with previous sensations; but this is a provoked recollection. Does a spontaneous or voluntary relation exist between these two groups of images? Examining the fullest monographs drawn up by physiologists[97] we find scarcely any information on this point. Cloquet, Müller, Valentin have reported cases of subjective sensations attributed by them to internal causes; but other physiologists, such as Ludwig, without denying these, are of opinion that sapid particles in the mouth, and odoriferous molecules on the mucous membrane of the nose, may act in a similar manner; so that the alleged images would, in fact, be sensations. ----- Footnote 97: See Von Vintschgau, art. “Geruch” and “Geschmack” in Hermann’s _Handbuch der Physiologie_, vol. iii.; Gley, art. “Gustation”; François-Franck, art. “Olfaction” in the _Dictionnaire encyclopédique des sciences médicales_. ----- Dreams may afford us a better starting-point. Among the numerous writers who have treated of this subject, some resolutely deny the existence of representations of taste and smell. It is impossible to accept this opinion. Though they are comparatively rare, examples may be found which are proof against all criticism. A person who, for hygienic reasons, has abstained from wine for several years, assures us that he has had a very clear impression of its taste in the course of a dream. We may recall the hypnagogic hallucinations so well described by A. Maury, who was subject to them; he mentions the taste of rancid oil, and the smell of burning as occurring apart from any objective cause. Among hallucinations properly so called, it is known that those of smell are of very frequent occurrence. Many authorities hesitate to admit those of taste, which they reduce to the status of mere illusions; but we know that the distinction formerly maintained between these two pathological manifestations has been, in our day, much disputed. 2. Internal sensations play a prominent part in the emotional life. Are these susceptible, in the normal condition, of spontaneous or voluntary revival? I have not been able to find any precise information on this point. In the pathological condition we can find numerous examples in hypochondriacs, hysterics, and neuropaths, in insane patients who complain of the suppression of some of their organs, of inversion of the stomach. In any case it would be necessary to determine the part played by the organ itself, and its actual state in the majority of these cases of revival, which is extremely difficult.