Organs of Touch.--In man, the nervous mechanism which governs touch is located in the folds of the dermis or in the skin. Special nerve endings, called the _tactile corpuscles_, are found there, each inclosed in a sheath or capsule of connective tissue. Inside is a complicated nerve ending, and axons pass inward to the central nervous system. The number of tactile corpuscles present in a given area of the skin determines the accuracy and ease with which objects may be known by touch. If you test the different parts of the body, as the back of the hand, the neck, the skin of the arm, of the back, or the tip of the tongue, with a pair of open dividers, a vast difference in the accuracy with which the two points may be distinguished is noticed. On the tip of the tongue, the two points need only be separated by 1/24 of an inch to be so distinguished. In the small of the back, a distance of 2 inches may be reached before the dividers feel like two points. Temperature, Pressure, Pain.--The feeling of temperature, pressure, and pain is determined by different end organs in the skin. Two kinds of nerve fibers exist in the skin, which give distinct sensations of heat and cold. These nerve endings can be located by careful experimentation. There are also areas of nerve endings which are sensitive to pressure, and still others, most numerous of all, sensitive to pain. Taste Organs.--The surface of the tongue is folded into a number of little projections known as papillae. These may be more easily found on your own tongue if a drop of vinegar is placed on its broad surface. In the folds, between these projections on the top and back part of the tongue, are located the organs of taste. These organs are called _taste buds_. [Illustration: _A_, isolated taste bud, from whose upper free end project the ends of the taste cells; _B_, supporting or protecting cell; _C_, sensory cell.] Each taste bud consists of a collection of spindle-shaped neurones, each cell tipped at its outer end with a hairlike projection. These cells send inward fibers to other cells, the fibers from which ultimately reach the brain. The sensory cells are surrounded by a number of projecting cells which are arranged in layers about them. Thus the organ in longitudinal section looks somewhat like an onion cut lengthwise.