. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. itk. Nerves in the skin; a, nerve fiht-r; b. tactile papillae, containing a tactile corpuscle ; e, papillae containing blood vessels. (After Benda.) Touch. — In animals having a hard outside coverinpr, such as certain worms, insects, and crustaceans, minute hairs, which are sensitive to touch, are found growing out from the body covering. At the base of these hairs are found nerve cells which send a nerve fiber inward to the central nervous system. Organs of Touch. — In man, the nervous mec
. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. itk. Nerves in the skin; a, nerve fiht-r; b. tactile papillae, containing a tactile corpuscle ; e, papillae containing blood vessels. (After Benda.) Touch. — In animals having a hard outside coverinpr, such as certain worms, insects, and crustaceans, minute hairs, which are sensitive to touch, are found growing out from the body covering. At the base of these hairs are found nerve cells which send a nerve fiber inward to the central nervous system. 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 end- ings, called the tactile corpus- cles, are there found. They are inclosed in a sheath, or capsule, of connective tissue. Inside is a complicated nerve ending, and ner\^e fibers are sent in- ward to the central nervous system. The number of tactile cor- puscles 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 liand. tho neck, the skin of the arm, of the back, or the tip of the tonf^uc, witli a i)air of open dividers, a vast difference in the accuracy with which tho two p(»ints may be distinguished is noticed. On the tip of the tongue, tlio two points need only be separated by 2V of an inch to be so distiiiKui.^hod. In the small of the back, a distance of two inches may be reached before the dividers feel like two points. Temperature, Pressure, Pain. — The feeling of temperature, pressure, and pain, the latter only in part, are determined by organs in the skin. Physiologists believe, however, that these organs are distinct from the apparatus which distinguishes touch. Taste Organs. —The surface of the tongue is folded into a num- ber of little projections known as papilhe. These may be more 419. Please note that these images are extracted from scan
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