Hyoid (Gr. letter υ, and εἰδος, form, resemblance). The bone at the root of the tongue, shaped like the Greek letter υ. Hypermetropia (Gr. ὑπέρ over, beyond, μέτρον, measure, and ώ̓ψ, the eye). Far-sightedness. Hypertrophy (Gr. ὑπέρ, over, and τροφή, nourishment). Excessive growth; thickening or enlargement of any part or organ. Incisor (Lat. _incido_, to cut). Applied to the four front teeth of both jaws, which have sharp, cutting edges. Incus. An anvil; the name of one of the bones of the middle ear. Indian Hemp. The common name of _Cannabis Indica_, an intoxicating drug known as _hasheesh_ and by other names in Eastern countries. Inferior Vena Cava. The chief vein of the lower part of the body. Inflammation (Lat. prefix _in_ and _flammo_, to flame). A redness or swelling of any part of the body with heat and pain. Insalivation (Lat. _in_ and _saliva_, the fluid of the mouth). The mingling of the saliva with the food during the act of chewing. Inspiration (Lat. _inspiro, spiratum_, to breathe in). The act of drawing in the breath. Intestine (Lat. _intus_, within). The part of the alimentary canal which is continuous with the lower end of the stomach; also called the bowels. Iris (Lat. _iris_, the rainbow). The thin, muscular ring which lies between the cornea and crystalline lens, giving the eye its special color. Jaundice (Fr. _jaunisse_, yellow). A disorder in which the skin and eyes assume a yellowish tint. Katabolism (Gr. καταβάλλω, to throw down). The process by means of which the more complex elements are rendered more simple and less complex. The opposite of _anabolism_. Labyrinth. The internal ear, so named from its many windings. Lacrymal Apparatus (Lat. _lacryma_, a tear). The organs for forming and carrying away the tears. Lacteals (Lat. _lac, lactis_, milk). The absorbent vessels of the small intestines. Laryngoscope (Gr. λάρυγξ, larynx, and σκοπέω, to behold). An instrument consisting of a mirror held in the throat, and a reflector to throw light on it, by which the interior of the larynx is brought into view. Larynx. The cartilaginous tube situated at the top of the windpipe. Lens. Literally, a lentil; a piece of transparent glass or other substance so shaped as either to converge or disperse the rays of light. Ligament (Lat. _ligo_, to bind). A strong, fibrous material binding bones or other solid parts together. Ligature (Lat. _ligo_, to bind). A thread of some material used in tying a cut or injured artery. Lobe. A round, projecting part of an organ, as of the liver, lungs, or brain. Lymph (Lat. _lympha_, pure water). The watery fluid conveyed by the lymphatic vessels. Lymphatic Vessels. A system of absorbent vessels. Malleus. Literally, the mallet; one of the small bones of the middle ear. Marrow. The soft, fatty substance contained in the cavities of bones. Mastication (Lat. _mastico_, to chew). The act of cutting and grinding the food to pieces by means of the teeth.