The important part played in human life by taste and the pleasure associated with it is well known. The careful choice and preparation of savory food--which has become an art in gastronomy and a branch of practical philosophy in gastrosophy--was just as important two thousand years ago with the Greeks and Romans as it is to-day in royal banquets or the Lucullic dinners of millionaires. The excitement that we see associated with this refined combination of rich foods and drinks, and that finds expression in so many speeches and toasts, has its philosophic root in the harmony of gustatory sensations and the varying play of stimuli that the delicate dishes and wines exercise on the organs of taste, the tongue and palate. The microscopic organs of these parts of the mouth are the gustatory papillæ--cup-shaped structures, covered with spindle-shaped "taste-cells," and having a narrow opening into the cavity of the mouth. When sapid matters, drinks and fluid or loose particles of food, touch the taste-cells, they excite the fine terminal branchlets of the gustatory nerve which enters the cells. As we find that there are similar structures in most of the higher animals, and that they also choose their food with some care, we may confidently assume that they have sensations of taste like man. However, no trace of this is found in many of the lower animals; in these cases it is impossible to lay down a line of demarcation between taste and smell. In man and the higher air-breathing vertebrates the seat of the sense of smell is in the nostrils; in man it is especially that part of the mucous lining of the nasal cavity which we call the "olfactory region" (the uppermost part of the nasal dividing wall, the superior and middle meatus). It is necessary for a sensation of smell that the odorous matter, or olfactory stimuli, be brought in a finely divided condition over the moist olfactory membranes. When they touch the olfactory cells--slender, rod-shaped cells with very fine hairs at the free end--they excite the ends of the olfactory nerve which are connected with the cells.