Lymph (L. lym´pha, spring-water). The colorless, watery fluid conveyed by the lymphatic vessels.

Lym-phat´ic Vessels. A system of absorbent vessels.

Mal´le-us (L.). Literally, the mallet; one of the small bones of the middle ear.

Mar´row. The soft, fatty substance contained in the central cavities of the bones: the spinal marrow, however, is composed of nervous tissue.

Mas-ti-ca´tion (L. mas´tico, to chew). The act of cutting and grinding the food to pieces by means of the teeth.

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. μικρός, mikros, small, and σκοπέω, skopeo, to

look at). An optical instrument which assists in the examination of minute objects.