s chloroform, ether,
laughing-gas, etc.

Anastomosis (Gr. ana, by, and stoma, a mouth). The intercommunication of
vessels.

Anatomy (Gr. anatemno, to cut up). The science which describes the
structure of living things. The word literally means dissection.

Antiseptic (Lat. _anti_, against, and _sepsis_, poison). Opposing or
counter-acting putrefaction.

Antrum (Lat. _antrum_, a cave). The cavity in the upper jaw.

Aorta (Gr. aorte, from aeipo, to raise up). The great artery that _rises
up_ from the left ventricle of the heart.

Aponeurosis (Gr. apo, from, and neuron, a nerve). A fibrous membranous
expansion of a tendon; the nerves and tendons were formerly thought to be
identical structures, both appearing as white cords.

Apoplexy (Gr. apoplechia, a sudden stroke). The escape of blood from a
ruptured blood-vessel into the substance of the brain.

Apparatus. A number of organs of various sizes and structures working
together for some special object.

Appendages (Lat. _ad_ and _pendeo_, to hang from). Something connected
with a part.

Aqueous Humor (Lat. _aqua_, water). The watery fluid occupying the space
between the cornea and crystalline lens of the eye.

Arachnoid Membrane (Gr. arachne, a spider, and eidos, like). The thin
covering of the brain and spinal cord, between the dura mater and the pia
mater.

Arbor Vitae. Literally, "the tree of life"; a name given to the peculiar
appearance presented by a section of the cerebellum.

Areolar (Lat. _areola_, a small space, dim. of _area_). A term applied to
a connective tissue containing _small spaces_.

Artery (Gr. aer, air, and tereo, to contain). A vessel by which blood is
carried away from the heart. It was supposed by the ancients to contain
only air, hence the name.

Articulation (Lat. _articulo_, to form a joint). The more or less movable
union of bones, etc.; a joint.

Arytenoid Cartilages (Gr. arytaina, a ladle). Two small cartilages of the
larynx, resembling the mouth of a pitcher.

Asphyxia (Gr. a, without, and sphixis, the pulse). Literally, "without
pulse." Condition caused by non-oxygenation of the blood.

Assimilation (Lat. _ad_, to, and _similis_, like). The conversion of food
into living tissue.

Asthma (Gr. asthma, a gasping). Spasmodic affection of the bronchial tubes
in which free respiration is interfered with, owing to their diminished
caliber.

Astigmatism (Gr. a, without, and stigma, a point). Irregular refraction of
the ey