ME-DUL´LA OB-LON-GA´TA. The "oblong marrow," or nervous cord, which is continuous with the spinal cord within the skull. MEM-BRA´NA TYM´PAN-I (L.). Literally, the membrane of the drum; a delicate partition separating the outer from the middle ear; it is sometimes incorrectly called the drum of the ear. MEM´BRANE. A thin layer of tissue serving to cover some part of the body. MI´CRO-SCOPE (Gr. [Greek: mikros], _mikros_, small, and [Greek: skopeô], _skopeo_, to {259} look at). An optical instrument which assists in the examination of minute objects. MO´LAR (L. _mo´la_, a mill). The name applied to the three back teeth of each side of the jaw; the grinders, or mill-like teeth. MO´TOR (L. _mo´veo_, _mo´tum_, to move). Causing motion; the name of those nerves which conduct to the muscles the stimulus which causes them to contract. MU´COUS MEMBRANE. The thin layer of tissue which covers those internal cavities or passages which communicate with the external air. MU´CUS. The glairy fluid which is secreted by mucous membranes, and which serves to keep them in a moist condition. MY-O´PI-A (Gr. [Greek: muô], _muo_, to contract, and [Greek: ôps], _ops_, the eye). A defect of vision dependent upon an eyeball that is too long, rendering distant objects indistinct; near-sight. NA´SAL (L. _na´sus_, the nose). Pertaining to the nose; the _nasal cavities_ contain the distribution of the special nerve of smell. NERVE (Gr. [Greek: neuron], _neuron_, a cord or string). A glistening, white cord of cylindrical shape, connecting the brain or spinal cord with some other organ of the body. NERVE CELL. A minute, round and ashen-gray cell found in the brain and other nervous centres. NERVE FI´BRE. An exceedingly slender thread of nervous tissue found in the various nervous organs, but especially in the nerves; it is of a white color. NU-TRI´TION (L. _nu´trio_, to nourish). The processes by which the nourishment of the body is accomplished. OE-SOPH´A-GUS (Gr.). Literally, that which carries food. The tube leading from the throat to the stomach; the gullet. O-LE-AG´I-NOUS (L. _o´leum_, oil). Of the nature of oil: applied to an important group of food-principles--the fats. OL-FAC´TO-RY (L. _olfa´cio_, to smell). Pertaining to the sense of smell. OPH-THAL´MO-SCOPE (Gr. [Greek: ophthalmos], _ophthalmos_, the eye, and [Greek: skopeô], _skopeo_, to look at). An instrument devised for examining the interior of the globe of the eye. OP´TIC (Gr. [Greek: optô], _opto_, to see). Pertaining to the sense of sight. OR´BIT (L. _or´bis_, the socket). The bony socket or cavity in which the eyeball is situated. OS´MOSE (Gr. [Greek: ôsmos], _osmos_, a thrusting or impulsion). The process by which liquids are impelled through a moist membrane. OS´SE-OUS (L. _os_, a bone). Consisting of, or resembling bone. PAL´ATE (L. _pala´tum_, the palate). The roof of the mouth, consisting of the hard and soft palate. {260} PAL´MAR. Relating to the palm of the hand.